<s>
They	O
search	O
the	O
World	O
Wide	O
Web	O
in	O
a	O
systematic	O
way	O
for	O
particular	O
information	O
specified	O
in	O
a	O
textual	O
web	O
search	O
query	B-Library
.	O
</s>
<s>
When	O
a	O
user	O
enters	O
a	O
query	B-Library
into	O
a	O
search	O
engine	O
,	O
the	O
engine	O
scans	O
its	O
index	B-Algorithm
of	O
web	O
pages	O
to	O
find	O
those	O
that	O
are	O
relevant	O
to	O
the	O
user	O
's	O
query	B-Library
.	O
</s>
<s>
Some	O
search	O
engines	O
also	O
mine	B-Application
data	I-Application
available	O
in	O
databases	O
or	O
open	O
directories	O
.	O
</s>
<s>
Unlike	O
web	B-Application
directories	I-Application
and	O
social	B-General_Concept
bookmarking	I-General_Concept
sites	I-General_Concept
,	O
which	O
are	O
maintained	O
by	O
human	O
editors	O
,	O
search	O
engines	O
also	O
maintain	O
real-time	B-General_Concept
information	O
by	O
running	O
an	O
algorithm	O
on	O
a	O
web	B-Application
crawler	I-Application
.	O
</s>
<s>
Any	O
internet-based	O
content	O
that	O
cannot	O
be	O
indexed	B-Application
and	O
searched	O
by	O
a	O
web	O
search	O
engine	O
falls	O
under	O
the	O
category	O
of	O
deep	O
web	O
.	O
</s>
<s>
+	O
Timeline	O
(	O
full	B-Application
list	I-Application
)	O
Year	O
Engine	O
Current	O
status1993W3CatalogALIWEBJumpStationWWW	O
Worm1994WebCrawlerGo.com,	O
redirects	O
to	O
DisneyLycosInfoseek	O
,	O
redirects	O
to	O
Disney1995Yahoo	O
!	O
</s>
<s>
Search	O
,	O
initially	O
a	O
search	O
function	O
for	O
Yahoo	B-Application
!	I-Application
</s>
<s>
DirectoryDaumSearch.chMagellanExciteMetaCrawlerAltaVista	O
,	O
acquired	O
by	O
Yahoo	B-Application
!	I-Application
</s>
<s>
in	O
2003	O
,	O
since	O
2013	O
redirects	O
to	O
Yahoo	B-Application
!	I-Application
1996RankDex	O
,	O
incorporated	O
into	O
Baidu	B-Application
in	O
2000DogpileHotBot	O
(	O
used	O
Inktomi	B-Application
search	O
technology	O
)	O
Ask	B-Application
Jeeves	I-Application
(	O
rebranded	O
ask.com	B-Application
)	O
1997AOL	O
NetFind	O
(	O
rebranded	O
AOL	B-Application
Search	I-Application
since	O
1999	O
)	O
Northern	O
LightYandex1998GoogleIxquick	O
as	O
Startpage.comMSN	O
Search	O
as	O
Bingempas	O
(	O
merged	O
with	O
NATE	B-Protocol
)	O
1999AlltheWeb	O
(	O
URL	O
redirected	O
to	O
Yahoo	B-Application
!	I-Application
</s>
<s>
Link	B-Application
analysis	I-Application
would	O
eventually	O
become	O
a	O
crucial	O
component	O
of	O
search	O
engines	O
through	O
algorithms	O
such	O
as	O
Hyper	O
Search	O
and	O
PageRank	B-Algorithm
.	O
</s>
<s>
The	O
first	O
internet	O
search	O
engines	O
predate	O
the	O
debut	O
of	O
the	O
Web	O
in	O
December	O
1990	O
:	O
WHOIS	B-Protocol
user	O
search	O
dates	O
back	O
to	O
1982	O
,	O
and	O
the	O
Knowbot	B-Protocol
Information	I-Protocol
Service	I-Protocol
multi-network	O
user	O
search	O
was	O
first	O
implemented	O
in	O
1989	O
.	O
</s>
<s>
The	O
first	O
well	O
documented	O
search	O
engine	O
that	O
searched	O
content	O
files	O
,	O
namely	O
FTP	B-Protocol
files	O
,	O
was	O
Archie	B-Protocol
,	O
which	O
debuted	O
on	O
10	O
September	O
1990	O
.	O
</s>
<s>
Prior	O
to	O
September	O
1993	O
,	O
the	O
World	O
Wide	O
Web	O
was	O
entirely	O
indexed	B-Application
by	O
hand	O
.	O
</s>
<s>
There	O
was	O
a	O
list	O
of	O
webservers	B-Application
edited	O
by	O
Tim	O
Berners-Lee	O
and	O
hosted	O
on	O
the	O
CERN	O
webserver	B-Application
.	O
</s>
<s>
One	O
snapshot	O
of	O
the	O
list	O
in	O
1992	O
remains	O
,	O
but	O
as	O
more	O
and	O
more	O
web	B-Application
servers	I-Application
went	O
online	O
the	O
central	O
list	O
could	O
no	O
longer	O
keep	O
up	O
.	O
</s>
<s>
On	O
the	O
NCSA	B-General_Concept
site	O
,	O
new	O
servers	O
were	O
announced	O
under	O
the	O
title	O
"	O
What	O
's	O
New	O
!	O
</s>
<s>
The	O
first	O
tool	O
used	O
for	O
searching	O
content	O
(	O
as	O
opposed	O
to	O
users	O
)	O
on	O
the	O
Internet	O
was	O
Archie	B-Protocol
.	O
</s>
<s>
It	O
was	O
created	O
by	O
Alan	O
Emtage	O
,	O
computer	B-General_Concept
science	I-General_Concept
student	O
at	O
McGill	O
University	O
in	O
Montreal	O
,	O
Quebec	O
,	O
Canada	O
.	O
</s>
<s>
The	O
program	O
downloaded	O
the	O
directory	O
listings	O
of	O
all	O
the	O
files	O
located	O
on	O
public	O
anonymous	O
FTP	B-Protocol
(	O
File	B-Protocol
Transfer	I-Protocol
Protocol	I-Protocol
)	O
sites	O
,	O
creating	O
a	O
searchable	O
database	O
of	O
file	O
names	O
;	O
however	O
,	O
Archie	B-Protocol
Search	I-Protocol
Engine	I-Protocol
did	O
not	O
index	B-Algorithm
the	O
contents	O
of	O
these	O
sites	O
since	O
the	O
amount	O
of	O
data	O
was	O
so	O
limited	O
it	O
could	O
be	O
readily	O
searched	O
manually	O
.	O
</s>
<s>
The	O
rise	O
of	O
Gopher	B-Protocol
(	O
created	O
in	O
1991	O
by	O
Mark	O
McCahill	O
at	O
the	O
University	O
of	O
Minnesota	O
)	O
led	O
to	O
two	O
new	O
search	O
programs	O
,	O
Veronica	B-Protocol
and	O
Jughead	B-Protocol
.	O
</s>
<s>
Like	O
Archie	B-Protocol
,	O
they	O
searched	O
the	O
file	O
names	O
and	O
titles	O
stored	O
in	O
Gopher	B-Protocol
index	B-Algorithm
systems	O
.	O
</s>
<s>
Veronica	B-Protocol
(	O
Very	O
Easy	O
Rodent-Oriented	O
Net-wide	O
Index	B-Algorithm
to	O
Computerized	O
Archives	O
)	O
provided	O
a	O
keyword	O
search	O
of	O
most	O
Gopher	B-Protocol
menu	O
titles	O
in	O
the	O
entire	O
Gopher	B-Protocol
listings	O
.	O
</s>
<s>
Jughead	B-Protocol
(	O
Jonzy	O
's	O
Universal	O
Gopher	B-Protocol
Hierarchy	O
Excavation	O
And	O
Display	O
)	O
was	O
a	O
tool	O
for	O
obtaining	O
menu	O
information	O
from	O
specific	O
Gopher	B-Protocol
servers	O
.	O
</s>
<s>
While	O
the	O
name	O
of	O
the	O
search	O
engine	O
"	O
Archie	B-Protocol
Search	I-Protocol
Engine	I-Protocol
"	O
was	O
not	O
a	O
reference	O
to	O
the	O
Archie	B-Protocol
comic	O
book	O
series	O
,	O
"	O
Veronica	B-Protocol
"	O
and	O
"	O
Jughead	B-Protocol
"	O
are	O
characters	O
in	O
the	O
series	O
,	O
thus	O
referencing	O
their	O
predecessor	O
.	O
</s>
<s>
Oscar	O
Nierstrasz	O
at	O
the	O
University	O
of	O
Geneva	O
wrote	O
a	O
series	O
of	O
Perl	B-Language
scripts	O
that	O
periodically	O
mirrored	O
these	O
pages	O
and	O
rewrote	O
them	O
into	O
a	O
standard	O
format	O
.	O
</s>
<s>
In	O
June	O
1993	O
,	O
Matthew	O
Gray	O
,	O
then	O
at	O
MIT	O
,	O
produced	O
what	O
was	O
probably	O
the	O
first	O
web	B-Application
robot	I-Application
,	O
the	O
Perl-based	O
World	B-Application
Wide	I-Application
Web	I-Application
Wanderer	I-Application
,	O
and	O
used	O
it	O
to	O
generate	O
an	O
index	B-Algorithm
called	O
"	O
Wandex	O
"	O
.	O
</s>
<s>
Aliweb	O
did	O
not	O
use	O
a	O
web	B-Application
robot	I-Application
,	O
but	O
instead	O
depended	O
on	O
being	O
notified	O
by	O
website	O
administrators	O
of	O
the	O
existence	O
at	O
each	O
site	O
of	O
an	O
index	B-Algorithm
file	O
in	O
a	O
particular	O
format	O
.	O
</s>
<s>
JumpStation	O
(	O
created	O
in	O
December	O
1993	O
by	O
Jonathon	O
Fletcher	O
)	O
used	O
a	O
web	B-Application
robot	I-Application
to	O
find	O
web	O
pages	O
and	O
to	O
build	O
its	O
index	B-Algorithm
,	O
and	O
used	O
a	O
web	B-General_Concept
form	I-General_Concept
as	O
the	O
interface	O
to	O
its	O
query	B-Library
program	O
.	O
</s>
<s>
It	O
was	O
thus	O
the	O
first	O
WWW	O
resource-discovery	O
tool	O
to	O
combine	O
the	O
three	O
essential	O
features	O
of	O
a	O
web	O
search	O
engine	O
(	O
crawling	O
,	O
indexing	B-Application
,	O
and	O
searching	O
)	O
as	O
described	O
below	O
.	O
</s>
<s>
Because	O
of	O
the	O
limited	O
resources	O
available	O
on	O
the	O
platform	O
it	O
ran	O
on	O
,	O
its	O
indexing	B-Application
and	O
hence	O
searching	O
were	O
limited	O
to	O
the	O
titles	O
and	O
headings	O
found	O
in	O
the	O
web	O
pages	O
the	O
crawler	B-Application
encountered	O
.	O
</s>
<s>
One	O
of	O
the	O
first	O
"	O
all	O
text	O
"	O
crawler-based	O
search	O
engines	O
was	O
WebCrawler	B-Application
,	O
which	O
came	O
out	O
in	O
1994	O
.	O
</s>
<s>
Also	O
in	O
1994	O
,	O
Lycos	B-Application
(	O
which	O
started	O
at	O
Carnegie	O
Mellon	O
University	O
)	O
was	O
launched	O
and	O
became	O
a	O
major	O
commercial	O
endeavor	O
.	O
</s>
<s>
The	O
first	O
popular	O
search	O
engine	O
on	O
the	O
Web	O
was	O
Yahoo	B-Application
!	I-Application
</s>
<s>
The	O
first	O
product	O
from	O
Yahoo	O
!,	O
founded	O
by	O
Jerry	O
Yang	O
and	O
David	O
Filo	O
in	O
January	O
1994	O
,	O
was	O
a	O
Web	B-Application
directory	I-Application
called	O
Yahoo	B-Application
!	I-Application
</s>
<s>
In	O
1995	O
,	O
a	O
search	O
function	O
was	O
added	O
,	O
allowing	O
users	O
to	O
search	O
Yahoo	B-Application
!	I-Application
</s>
<s>
It	O
became	O
one	O
of	O
the	O
most	O
popular	O
ways	O
for	O
people	O
to	O
find	O
web	O
pages	O
of	O
interest	O
,	O
but	O
its	O
search	O
function	O
operated	O
on	O
its	O
web	B-Application
directory	I-Application
,	O
rather	O
than	O
its	O
full-text	O
copies	O
of	O
web	O
pages	O
.	O
</s>
<s>
These	O
included	O
Magellan	B-Application
,	O
Excite	B-Application
,	O
Infoseek	O
,	O
Inktomi	B-Application
,	O
Northern	O
Light	O
,	O
and	O
AltaVista	O
.	O
</s>
<s>
In	O
1996	O
,	O
Robin	O
Li	O
developed	O
the	O
RankDex	O
site-scoring	O
algorithm	O
for	O
search	O
engines	O
results	O
page	B-Algorithm
ranking	I-Algorithm
and	O
received	O
a	O
US	O
patent	O
for	O
the	O
technology	O
.	O
</s>
<s>
It	O
was	O
the	O
first	O
search	O
engine	O
that	O
used	O
hyperlinks	O
to	O
measure	O
the	O
quality	O
of	O
websites	O
it	O
was	O
indexing	B-Application
,	O
predating	O
the	O
very	O
similar	O
algorithm	O
patent	O
filed	O
by	O
Google	B-Application
two	O
years	O
later	O
in	O
1998	O
.	O
</s>
<s>
Larry	O
Page	O
referenced	O
Li	O
's	O
work	O
in	O
some	O
of	O
his	O
U.S.	O
patents	O
for	O
PageRank	B-Algorithm
.	O
</s>
<s>
Li	O
later	O
used	O
his	O
Rankdex	O
technology	O
for	O
the	O
Baidu	B-Application
search	I-Application
engine	O
,	O
which	O
was	O
founded	O
by	O
him	O
in	O
China	O
and	O
launched	O
in	O
2000	O
.	O
</s>
<s>
In	O
1996	O
,	O
Netscape	B-Protocol
was	O
looking	O
to	O
give	O
a	O
single	O
search	O
engine	O
an	O
exclusive	O
deal	O
as	O
the	O
featured	O
search	O
engine	O
on	O
Netscape	B-Protocol
's	O
web	O
browser	O
.	O
</s>
<s>
There	O
was	O
so	O
much	O
interest	O
that	O
instead	O
Netscape	B-Protocol
struck	O
deals	O
with	O
five	O
of	O
the	O
major	O
search	O
engines	O
:	O
for	O
$5	O
million	O
a	O
year	O
,	O
each	O
search	O
engine	O
would	O
be	O
in	O
rotation	O
on	O
the	O
Netscape	B-Protocol
search	O
engine	O
page	O
.	O
</s>
<s>
The	O
five	O
engines	O
were	O
Yahoo	O
!,	O
Magellan	B-Application
,	O
Lycos	B-Application
,	O
Infoseek	O
,	O
and	O
Excite	B-Application
.	O
</s>
<s>
Google	B-Application
adopted	O
the	O
idea	O
of	O
selling	O
search	O
terms	O
in	O
1998	O
,	O
from	O
a	O
small	O
search	O
engine	O
company	O
named	O
goto.com	B-Application
.	O
</s>
<s>
Many	O
search	O
engine	O
companies	O
were	O
caught	O
up	O
in	O
the	O
dot-com	O
bubble	B-Algorithm
,	O
a	O
speculation-driven	O
market	O
boom	O
that	O
peaked	O
in	O
March	O
2000	O
.	O
</s>
<s>
Around	O
2000	O
,	O
Google	B-Application
's	I-Application
search	I-Application
engine	I-Application
rose	O
to	O
prominence	O
.	O
</s>
<s>
The	O
company	O
achieved	O
better	O
results	O
for	O
many	O
searches	O
with	O
an	O
algorithm	O
called	O
PageRank	B-Algorithm
,	O
as	O
was	O
explained	O
in	O
the	O
paper	O
Anatomy	O
of	O
a	O
Search	O
Engine	O
written	O
by	O
Sergey	O
Brin	O
and	O
Larry	O
Page	O
,	O
the	O
later	O
founders	O
of	O
Google	B-Application
.	I-Application
</s>
<s>
This	O
iterative	B-Algorithm
algorithm	I-Algorithm
ranks	O
web	O
pages	O
based	O
on	O
the	O
number	O
and	O
PageRank	B-Algorithm
of	O
other	O
web	O
sites	O
and	O
pages	O
that	O
link	O
there	O
,	O
on	O
the	O
premise	O
that	O
good	O
or	O
desirable	O
pages	O
are	O
linked	O
to	O
more	O
than	O
others	O
.	O
</s>
<s>
Larry	O
Page	O
's	O
patent	O
for	O
PageRank	B-Algorithm
cites	O
Robin	O
Li	O
's	O
earlier	O
RankDex	O
patent	O
as	O
an	O
influence	O
.	O
</s>
<s>
Google	B-Application
also	O
maintained	O
a	O
minimalist	O
interface	O
to	O
its	O
search	O
engine	O
.	O
</s>
<s>
In	O
fact	O
,	O
the	B-Application
Google	I-Application
search	O
engine	O
became	O
so	O
popular	O
that	O
spoof	O
engines	O
emerged	O
such	O
as	O
Mystery	B-Application
Seeker	I-Application
.	O
</s>
<s>
By	O
2000	O
,	O
Yahoo	B-Application
!	I-Application
</s>
<s>
was	O
providing	O
search	O
services	O
based	O
on	O
Inktomi	B-Application
's	O
search	O
engine	O
.	O
</s>
<s>
Yahoo	B-Application
!	I-Application
</s>
<s>
acquired	O
Inktomi	B-Application
in	O
2002	O
,	O
and	O
Overture	B-Application
(	O
which	O
owned	O
AlltheWeb	B-Application
and	O
AltaVista	O
)	O
in	O
2003	O
.	O
</s>
<s>
Yahoo	B-Application
!	I-Application
</s>
<s>
switched	O
to	O
Google	B-Application
's	I-Application
search	I-Application
engine	I-Application
until	O
2004	O
,	O
when	O
it	O
launched	O
its	O
own	O
search	O
engine	O
based	O
on	O
the	O
combined	O
technologies	O
of	O
its	O
acquisitions	O
.	O
</s>
<s>
Microsoft	O
first	O
launched	O
MSN	B-Application
Search	I-Application
in	O
the	O
fall	O
of	O
1998	O
using	O
search	O
results	O
from	O
Inktomi	B-Application
.	O
</s>
<s>
In	O
early	O
1999	O
the	O
site	O
began	O
to	O
display	O
listings	O
from	O
Looksmart	O
,	O
blended	O
with	O
results	O
from	O
Inktomi	B-Application
.	O
</s>
<s>
For	O
a	O
short	O
time	O
in	O
1999	O
,	O
MSN	B-Application
Search	I-Application
used	O
results	O
from	O
AltaVista	O
instead	O
.	O
</s>
<s>
In	O
2004	O
,	O
Microsoft	O
began	O
a	O
transition	O
to	O
its	O
own	O
search	O
technology	O
,	O
powered	O
by	O
its	O
own	O
web	B-Application
crawler	I-Application
(	O
called	O
msnbot	B-Protocol
)	O
.	O
</s>
<s>
Microsoft	O
's	O
rebranded	O
search	O
engine	O
,	O
Bing	B-Application
,	O
was	O
launched	O
on	O
June	O
1	O
,	O
2009	O
.	O
</s>
<s>
On	O
July	O
29	O
,	O
2009	O
,	O
Yahoo	B-Application
!	I-Application
</s>
<s>
and	O
Microsoft	O
finalized	O
a	O
deal	O
in	O
which	O
Yahoo	B-Application
!	I-Application
</s>
<s>
Search	O
would	O
be	O
powered	O
by	O
Microsoft	B-Application
Bing	I-Application
technology	O
.	O
</s>
<s>
As	O
of	O
2019	O
,	O
active	O
search	O
engine	O
crawlers	O
include	O
those	O
of	O
Google	B-Application
,	O
Sogou	O
,	O
Baidu	B-Application
,	O
Bing	B-Application
,	O
Gigablast	B-Application
,	O
Mojeek	B-Application
,	O
DuckDuckGo	B-Application
and	O
Yandex	B-Application
.	O
</s>
<s>
Web	O
search	O
engines	O
get	O
their	O
information	O
by	O
web	B-Application
crawling	I-Application
from	O
site	O
to	O
site	O
.	O
</s>
<s>
After	O
checking	O
for	O
robots.txt	O
and	O
either	O
finding	O
it	O
or	O
not	O
,	O
the	O
spider	O
sends	O
certain	O
information	O
back	O
to	O
be	O
indexed	B-Application
depending	O
on	O
many	O
factors	O
,	O
such	O
as	O
the	O
titles	O
,	O
page	O
content	O
,	O
JavaScript	B-Language
,	O
Cascading	B-Language
Style	I-Language
Sheets	I-Language
(	O
CSS	B-Language
)	O
,	O
headings	O
,	O
or	O
its	O
metadata	O
in	O
HTML	B-Language
meta	O
tags	O
.	O
</s>
<s>
After	O
a	O
certain	O
number	O
of	O
pages	O
crawled	O
,	O
amount	O
of	O
data	O
indexed	B-Application
,	O
or	O
time	O
spent	O
on	O
the	O
website	O
,	O
the	O
spider	O
stops	O
crawling	O
and	O
moves	O
on	O
.	O
</s>
<s>
"[N]o	O
web	B-Application
crawler	I-Application
may	O
actually	O
crawl	O
the	O
entire	O
reachable	O
web	O
.	O
</s>
<s>
Indexing	B-Application
means	O
associating	O
words	O
and	O
other	O
definable	O
tokens	O
found	O
on	O
web	O
pages	O
to	O
their	O
domain	O
names	O
and	O
HTML-based	O
fields	O
.	O
</s>
<s>
The	O
associations	O
are	O
made	O
in	O
a	O
public	O
database	O
,	O
made	O
available	O
for	O
web	O
search	O
queries	B-Library
.	O
</s>
<s>
A	O
query	B-Library
from	O
a	O
user	O
can	O
be	O
a	O
single	O
word	O
,	O
multiple	O
words	O
or	O
a	O
sentence	O
.	O
</s>
<s>
The	O
index	B-Algorithm
helps	O
find	O
information	O
relating	O
to	O
the	O
query	B-Library
as	O
quickly	O
as	O
possible	O
.	O
</s>
<s>
Some	O
of	O
the	O
techniques	O
for	O
indexing	B-Application
,	O
and	O
caching	B-General_Concept
are	O
trade	O
secrets	O
,	O
whereas	O
web	B-Application
crawling	I-Application
is	O
a	O
straightforward	O
process	O
of	O
visiting	O
all	O
sites	O
on	O
a	O
systematic	O
basis	O
.	O
</s>
<s>
Between	O
visits	O
by	O
the	O
spider	O
,	O
the	O
cached	B-General_Concept
version	O
of	O
the	O
page	O
(	O
some	O
or	O
all	O
the	O
content	O
needed	O
to	O
render	O
it	O
)	O
stored	O
in	O
the	O
search	O
engine	O
working	O
memory	O
is	O
quickly	O
sent	O
to	O
an	O
inquirer	O
.	O
</s>
<s>
In	O
this	O
case	O
,	O
the	O
page	O
may	O
differ	O
from	O
the	O
search	O
terms	O
indexed	B-Application
.	O
</s>
<s>
The	O
cached	B-General_Concept
page	O
holds	O
the	O
appearance	O
of	O
the	O
version	O
whose	O
words	O
were	O
previously	O
indexed	B-Application
,	O
so	O
a	O
cached	B-General_Concept
version	O
of	O
a	O
page	O
can	O
be	O
useful	O
to	O
the	O
website	O
when	O
the	O
actual	O
page	O
has	O
been	O
lost	O
,	O
but	O
this	O
problem	O
is	O
also	O
considered	O
a	O
mild	O
form	O
of	O
linkrot	O
.	O
</s>
<s>
Typically	O
when	O
a	O
user	O
enters	O
a	O
query	B-Library
into	O
a	O
search	O
engine	O
it	O
is	O
a	O
few	O
keywords	O
.	O
</s>
<s>
The	O
index	B-Algorithm
already	O
has	O
the	O
names	O
of	O
the	O
sites	O
containing	O
the	B-Application
keywords	I-Application
,	O
and	O
these	O
are	O
instantly	O
obtained	O
from	O
the	O
index	B-Algorithm
.	O
</s>
<s>
The	O
real	O
processing	O
load	O
is	O
in	O
generating	O
the	O
web	O
pages	O
that	O
are	O
the	O
search	O
results	O
list	O
:	O
Every	O
page	O
in	O
the	O
entire	O
list	O
must	O
be	O
weighted	B-General_Concept
according	O
to	O
information	O
in	O
the	O
indexes	O
.	O
</s>
<s>
Then	O
the	O
top	O
search	O
result	O
item	O
requires	O
the	O
lookup	O
,	O
reconstruction	O
,	O
and	O
markup	O
of	O
the	O
snippets	B-Application
showing	O
the	O
context	O
of	O
the	B-Application
keywords	I-Application
matched	O
.	O
</s>
<s>
Beyond	O
simple	O
keyword	O
lookups	O
,	O
search	O
engines	O
offer	O
their	O
own	O
GUI	B-Application
-	O
or	O
command-driven	O
operators	O
and	O
search	O
parameters	O
to	O
refine	O
the	O
search	O
results	O
.	O
</s>
<s>
These	O
provide	O
the	O
necessary	O
controls	O
for	O
the	O
user	O
engaged	O
in	O
the	O
feedback	O
loop	O
users	O
create	O
by	O
filtering	O
and	O
weighting	B-General_Concept
while	O
refining	O
the	O
search	O
results	O
,	O
given	O
the	O
initial	O
pages	O
of	O
the	O
first	O
search	O
results	O
.	O
</s>
<s>
Most	O
search	O
engines	O
support	O
the	O
use	O
of	O
the	O
boolean	O
operators	O
AND	O
,	O
OR	O
and	O
NOT	O
to	O
help	O
end	O
users	O
refine	O
the	O
search	O
query	B-Library
.	O
</s>
<s>
Some	O
search	O
engines	O
provide	O
an	O
advanced	O
feature	O
called	O
proximity	B-Application
search	I-Application
,	O
which	O
allows	O
users	O
to	O
define	O
the	O
distance	O
between	O
keywords	O
.	O
</s>
<s>
The	O
other	O
is	O
a	O
system	O
that	O
generates	O
an	O
"	O
inverted	B-Algorithm
index	I-Algorithm
"	O
by	O
analyzing	O
texts	O
it	O
locates	O
.	O
</s>
<s>
Local	B-Application
search	I-Application
is	O
the	O
process	O
that	O
optimizes	O
the	O
efforts	O
of	O
local	O
businesses	O
.	O
</s>
<s>
,	O
Google	B-Application
is	O
by	O
far	O
the	O
world	O
's	O
most	O
used	O
search	O
engine	O
,	O
with	O
a	O
market	O
share	O
of	O
90.6	O
%	O
,	O
and	O
the	O
world	O
's	O
other	O
most	O
used	O
search	O
engines	O
were	O
Bing	B-Application
,	O
Yahoo	O
!,	O
Baidu	B-Application
,	O
Yandex	B-Application
,	O
and	O
DuckDuckGo	B-Application
.	O
</s>
<s>
In	O
Russia	O
,	O
Yandex	B-Application
has	O
a	O
market	O
share	O
of	O
62.6	O
%	O
,	O
compared	O
to	O
Google	B-Application
's	I-Application
28.3	O
%	O
.	O
</s>
<s>
And	O
Yandex	B-Application
is	O
the	O
second	O
most	O
used	O
search	O
engine	O
on	O
smartphones	O
in	O
Asia	O
and	O
Europe	O
.	O
</s>
<s>
In	O
China	O
,	O
Baidu	B-Application
is	O
the	O
most	O
popular	O
search	O
engine	O
.	O
</s>
<s>
South	O
Korea	O
's	O
homegrown	O
search	O
portal	O
,	O
Naver	B-Protocol
,	O
is	O
used	O
for	O
62.8	O
%	O
of	O
online	O
searches	O
in	O
the	O
country	O
.	O
</s>
<s>
Yahoo	B-Application
!	I-Application
</s>
<s>
Japan	O
and	O
Yahoo	B-Application
!	I-Application
</s>
<s>
China	O
is	O
one	O
of	O
few	O
countries	O
where	O
Google	B-Application
is	O
not	O
in	O
the	O
top	O
three	O
web	O
search	O
engines	O
for	O
market	O
share	O
.	O
</s>
<s>
Google	B-Application
was	O
previously	O
a	O
top	O
search	O
engine	O
in	O
China	O
,	O
but	O
withdrew	O
after	O
a	O
disagreement	O
with	O
the	O
government	O
over	O
censorship	O
,	O
and	O
a	O
cyberattack	O
.	O
</s>
<s>
But	O
Bing	B-Application
is	O
in	O
top	O
three	O
web	O
search	O
engine	O
with	O
a	O
market	O
share	O
of	O
14.95	O
%	O
.	O
</s>
<s>
Baidu	B-Application
is	O
on	O
top	O
with	O
49.1	O
℅	O
market	O
share	O
.	O
</s>
<s>
Most	O
countries	O
 '	O
markets	O
in	O
the	O
European	O
Union	O
are	O
dominated	O
by	O
Google	B-Application
,	O
except	O
for	O
the	O
Czech	O
Republic	O
,	O
where	O
Seznam	B-Application
is	O
a	O
strong	O
competitor	O
.	O
</s>
<s>
For	O
example	O
,	O
Google	B-Application
will	O
not	O
surface	O
certain	O
neo-Nazi	O
websites	O
in	O
France	O
and	O
Germany	O
,	O
where	O
Holocaust	O
denial	O
is	O
illegal	O
.	O
</s>
<s>
Indexing	B-Application
algorithms	O
of	O
major	O
search	O
engines	O
skew	O
towards	O
coverage	O
of	O
U.S.-based	O
sites	O
,	O
rather	O
than	O
websites	O
from	O
non-U.S.	O
countries	O
.	O
</s>
<s>
Google	B-Application
Bombing	O
is	O
one	O
example	O
of	O
an	O
attempt	O
to	O
manipulate	O
search	O
results	O
for	O
political	O
,	O
social	O
or	O
commercial	O
reasons	O
.	O
</s>
<s>
There	O
has	O
been	O
concern	O
raised	O
that	O
search	O
engines	O
such	O
as	O
Google	B-Application
and	O
Bing	B-Application
provide	O
customized	O
results	O
based	O
on	O
the	O
user	O
's	O
activity	O
history	O
,	O
leading	O
to	O
what	O
has	O
been	O
termed	O
echo	O
chambers	O
or	O
filter	B-Algorithm
bubbles	I-Algorithm
by	O
Eli	O
Pariser	O
in	O
2011	O
.	O
</s>
<s>
According	O
to	O
Eli	O
Pariser	O
users	O
get	O
less	O
exposure	O
to	O
conflicting	O
viewpoints	O
and	O
are	O
isolated	O
intellectually	O
in	O
their	O
own	O
informational	B-Algorithm
bubble	I-Algorithm
.	O
</s>
<s>
Since	O
this	O
problem	O
has	O
been	O
identified	O
,	O
competing	O
search	O
engines	O
have	O
emerged	O
that	O
seek	O
to	O
avoid	O
this	O
problem	O
by	O
not	O
tracking	O
or	O
"	O
bubbling	O
"	O
users	O
,	O
such	O
as	O
DuckDuckGo	B-Application
.	O
</s>
<s>
However	O
many	O
scholars	O
have	O
questioned	O
Pariser	O
's	O
view	O
,	O
finding	O
that	O
there	O
is	O
little	O
evidence	O
for	O
the	B-Algorithm
filter	I-Algorithm
bubble	I-Algorithm
.	O
</s>
<s>
On	O
the	O
contrary	O
,	O
a	O
number	O
of	O
studies	O
trying	O
to	O
verify	O
the	O
existence	O
of	O
filter	B-Algorithm
bubbles	I-Algorithm
have	O
found	O
only	O
minor	O
levels	O
of	O
personalisation	O
in	O
search	O
,	O
that	O
most	O
people	O
encounter	O
a	O
range	O
of	O
views	O
when	O
browsing	O
online	O
,	O
and	O
that	O
Google	B-Application
news	O
tends	O
to	O
promote	O
mainstream	O
established	O
news	O
outlets	O
.	O
</s>
<s>
The	O
global	O
growth	O
of	O
the	O
Internet	O
and	O
electronic	O
media	O
in	O
the	O
Arab	O
and	O
Muslim	O
World	O
during	O
the	O
last	O
decade	O
has	O
encouraged	O
Islamic	O
adherents	O
in	O
the	O
Middle	O
East	O
and	O
Asian	O
sub-continent	O
,	O
to	O
attempt	O
their	O
own	O
search	O
engines	O
,	O
their	O
own	O
filtered	O
search	O
portals	O
that	O
would	O
enable	O
users	O
to	O
perform	O
safe	B-Protocol
searches	I-Protocol
.	O
</s>
<s>
ImHalal	B-Application
came	O
online	O
in	O
September	O
2011	O
.	O
</s>
<s>
Halalgoogling	B-Application
came	O
online	O
in	O
July	O
2013	O
.	O
</s>
<s>
These	O
use	O
haram	O
filters	O
on	O
the	O
collections	O
from	O
Google	B-Application
and	O
Bing	B-Application
(	O
and	O
others	O
)	O
.	O
</s>
<s>
Other	O
religion-oriented	O
search	O
engines	O
are	O
Jewogle	O
,	O
the	O
Jewish	O
version	O
of	O
Google	B-Application
,	O
and	O
SeekFind.org,	O
which	O
is	O
Christian	O
.	O
</s>
<s>
While	O
search	O
engine	O
submission	O
is	O
sometimes	O
presented	O
as	O
a	O
way	O
to	O
promote	O
a	O
website	O
,	O
it	O
generally	O
is	O
not	O
necessary	O
because	O
the	O
major	O
search	O
engines	O
use	O
web	B-Application
crawlers	I-Application
that	O
will	O
eventually	O
find	O
most	O
web	O
sites	O
on	O
the	O
Internet	O
without	O
assistance	O
.	O
</s>
<s>
However	O
,	O
John	O
Mueller	O
of	O
Google	B-Application
has	O
stated	O
that	O
this	O
"	O
can	O
lead	O
to	O
a	O
tremendous	O
number	O
of	O
unnatural	O
links	O
for	O
your	O
site	O
"	O
with	O
a	O
negative	O
impact	O
on	O
site	O
ranking	O
.	O
</s>
<s>
The	O
first	O
web	O
search	O
engines	O
was	O
Archie	B-Protocol
,	O
created	O
in	O
1990	O
by	O
Alan	O
Emtage	O
,	O
a	O
student	O
at	O
McGill	O
University	O
in	O
Montreal	O
.	O
</s>
<s>
The	O
author	O
originally	O
wanted	O
to	O
call	O
the	O
program	O
"	O
archives	O
,	O
"	O
but	O
had	O
to	O
shorten	O
it	O
to	O
comply	O
with	O
the	O
Unix	O
world	O
standard	O
of	O
assigning	O
programs	O
and	O
files	O
short	O
,	O
cryptic	O
names	O
such	O
as	O
grep	O
,	O
cat	O
,	O
troff	O
,	O
sed	O
,	O
awk	O
,	O
perl	B-Language
,	O
and	O
so	O
on	O
.	O
</s>
<s>
The	O
primary	O
method	O
of	O
storing	O
and	O
retrieving	O
files	O
was	O
via	O
the	O
File	B-Protocol
Transfer	I-Protocol
Protocol	I-Protocol
(	O
FTP	B-Protocol
)	O
.	O
</s>
<s>
He	O
sets	O
up	O
a	O
program	O
on	O
his	O
computer	O
,	O
called	O
an	O
FTP	B-Protocol
server	I-Protocol
.	O
</s>
<s>
When	O
someone	O
on	O
the	O
Internet	O
wants	O
to	O
retrieve	O
a	O
file	O
from	O
this	O
computer	O
,	O
he	O
or	O
she	O
connects	O
to	O
it	O
via	O
another	O
program	O
called	O
an	O
FTP	B-Protocol
client	I-Protocol
.	O
</s>
<s>
Any	O
FTP	B-Protocol
client	I-Protocol
program	O
can	O
connect	O
with	O
any	O
FTP	B-Protocol
server	I-Protocol
program	O
as	O
long	O
as	O
the	O
client	O
and	O
server	O
programs	O
both	O
fully	O
follow	O
the	O
specifications	O
set	O
forth	O
in	O
the	O
FTP	B-Protocol
protocol	I-Protocol
.	O
</s>
<s>
Initially	O
,	O
anyone	O
who	O
wanted	O
to	O
share	O
a	O
file	O
had	O
to	O
set	O
up	O
an	O
FTP	B-Protocol
server	I-Protocol
in	O
order	O
to	O
make	O
the	O
file	O
available	O
to	O
others	O
.	O
</s>
<s>
Later	O
,	O
"	O
anonymous	O
"	O
FTP	B-Protocol
sites	I-Protocol
became	O
repositories	O
for	O
files	O
,	O
allowing	O
all	O
users	O
to	O
post	O
and	O
retrieve	O
them	O
.	O
</s>
<s>
Even	O
with	O
archive	O
sites	O
,	O
many	O
important	O
files	O
were	O
still	O
scattered	O
on	O
small	O
FTP	B-Protocol
servers	I-Protocol
.	O
</s>
<s>
Archie	B-Protocol
changed	O
all	O
that	O
.	O
</s>
<s>
It	O
combined	O
a	O
script-based	O
data	O
gatherer	O
,	O
which	O
fetched	O
site	O
listings	O
of	O
anonymous	O
FTP	B-Protocol
files	O
,	O
with	O
a	O
regular	O
expression	O
matcher	O
for	O
retrieving	O
file	O
names	O
matching	O
a	O
user	O
query	B-Library
.	O
</s>
<s>
(	O
4	O
)	O
In	O
other	O
words	O
,	O
Archie	B-Protocol
's	O
gatherer	O
scoured	O
FTP	B-Protocol
sites	I-Protocol
across	O
the	O
Internet	O
and	O
indexed	B-Application
all	O
of	O
the	O
files	O
it	O
found	O
.	O
</s>
<s>
In	O
1993	O
,	O
the	O
University	O
of	O
Nevada	O
System	O
Computing	O
Services	O
group	O
developed	O
Veronica	B-Protocol
.	O
</s>
<s>
It	O
was	O
created	O
as	O
a	O
type	O
of	O
searching	O
device	O
similar	O
to	O
Archie	B-Protocol
but	O
for	O
Gopher	B-Protocol
files	O
.	O
</s>
<s>
Another	O
Gopher	B-Protocol
search	O
service	O
,	O
called	O
Jughead	B-Protocol
,	O
appeared	O
a	O
little	O
later	O
,	O
probably	O
for	O
the	O
sole	O
purpose	O
of	O
rounding	O
out	O
the	O
comic-strip	O
triumvirate	O
.	O
</s>
<s>
Jughead	B-Protocol
is	O
an	O
acronym	O
for	O
Jonzy	O
's	O
Universal	O
Gopher	B-Protocol
Hierarchy	O
Excavation	O
and	O
Display	O
,	O
although	O
,	O
like	O
Veronica	B-Protocol
,	O
it	O
is	O
probably	O
safe	O
to	O
assume	O
that	O
the	O
creator	O
backed	O
into	O
the	O
acronym	O
.	O
</s>
<s>
Jughead	B-Protocol
's	O
functionality	O
was	O
pretty	O
much	O
identical	O
to	O
Veronica	B-Protocol
's	O
,	O
although	O
it	O
appears	O
to	O
be	O
a	O
little	O
rougher	O
around	O
the	O
edges	O
.	O
</s>
<s>
The	O
World	B-Application
Wide	I-Application
Web	I-Application
Wanderer	I-Application
,	O
developed	O
by	O
Matthew	O
Gray	O
in	O
1993	O
was	O
the	O
first	O
robot	O
on	O
the	O
Web	O
and	O
was	O
designed	O
to	O
track	O
the	O
Web	O
's	O
growth	O
.	O
</s>
<s>
Initially	O
,	O
the	O
Wanderer	O
counted	O
only	O
Web	B-Application
servers	I-Application
,	O
but	O
shortly	O
after	O
its	O
introduction	O
,	O
it	O
started	O
to	O
capture	O
URLs	O
as	O
it	O
went	O
along	O
.	O
</s>
<s>
In	O
response	O
to	O
the	O
Wanderer	O
,	O
Martijn	O
Koster	O
created	O
Archie-Like	O
Indexing	B-Application
of	O
the	O
Web	O
,	O
or	O
ALIWEB	O
,	O
in	O
October	O
1993	O
.	O
</s>
<s>
As	O
the	O
name	O
implies	O
,	O
ALIWEB	O
was	O
the	O
HTTP	O
equivalent	O
of	O
Archie	B-Protocol
,	O
and	O
because	O
of	O
this	O
,	O
it	O
is	O
still	O
unique	O
in	O
many	O
ways	O
.	O
</s>
<s>
Instead	O
,	O
webmasters	O
of	O
participating	O
sites	O
post	O
their	O
own	O
index	B-Algorithm
information	O
for	O
each	O
page	O
they	O
want	O
listed	O
.	O
</s>
<s>
The	O
primary	O
disadvantage	O
is	O
that	O
a	O
special	O
indexing	B-Application
file	O
must	O
be	O
submitted	O
.	O
</s>
<s>
This	O
leads	O
to	O
a	O
relatively	O
small	O
database	O
,	O
which	O
meant	O
that	O
users	O
are	O
less	O
likely	O
to	O
search	O
ALIWEB	O
than	O
one	O
of	O
the	O
large	O
bot-based	O
sites	O
.	O
</s>
<s>
This	O
Catch-22	O
has	O
been	O
somewhat	O
offset	O
by	O
incorporating	O
other	O
databases	O
into	O
the	O
ALIWEB	O
search	O
,	O
but	O
it	O
still	O
does	O
not	O
have	O
the	O
mass	O
appeal	O
of	O
search	O
engines	O
such	O
as	O
Yahoo	B-Application
!	I-Application
</s>
<s>
or	O
Lycos	B-Application
.	O
</s>
<s>
Excite	B-Application
,	O
initially	O
called	O
Architext	O
,	O
was	O
started	O
by	O
six	O
Stanford	O
undergraduates	O
in	O
February	O
1993	O
.	O
</s>
<s>
At	O
the	O
time	O
,	O
the	O
software	O
was	O
called	O
Architext	O
,	O
but	O
it	O
now	O
goes	O
by	O
the	O
name	O
of	O
Excite	B-Application
for	O
Web	B-Application
Servers	I-Application
.	O
</s>
<s>
Excite	B-Application
was	O
the	O
first	O
serious	O
commercial	O
search	O
engine	O
which	O
launched	O
in	O
1995	O
.	O
</s>
<s>
In	O
2001	O
Excite	B-Application
and	O
@Home	O
went	O
bankrupt	O
and	O
InfoSpace	O
bought	O
Excite	B-Application
for	O
$10	O
million	O
.	O
</s>
<s>
They	O
called	O
the	O
collection	O
of	O
pages	O
Yahoo	B-Application
!	I-Application
</s>
<s>
Their	O
official	O
explanation	O
for	O
the	O
name	O
choice	O
was	O
that	O
they	O
considered	O
themselves	O
to	O
be	O
a	O
pair	O
of	O
yahoos	B-Application
.	O
</s>
<s>
In	O
order	O
to	O
aid	O
in	O
data	O
retrieval	O
,	O
Yahoo	B-Application
!	I-Application
</s>
<s>
(	O
www.yahoo.com	O
)	O
became	O
a	O
searchable	O
directory	O
.	O
</s>
<s>
Because	O
Yahoo	B-Application
!	I-Application
</s>
<s>
entries	O
were	O
entered	O
and	O
categorized	O
manually	O
,	O
Yahoo	B-Application
!	I-Application
</s>
<s>
Yahoo	B-Application
!	I-Application
</s>
<s>
Searching	O
Yahoo	B-Application
!	I-Application
</s>
<s>
or	O
the	O
Galaxy	O
was	O
much	O
more	O
effective	O
because	O
they	O
contained	O
additional	O
descriptive	O
information	O
about	O
the	O
indexed	B-Application
sites	O
.	O
</s>
<s>
At	O
Carnegie	O
Mellon	O
University	O
during	O
July	O
1994	O
,	O
Michael	O
Mauldin	O
,	O
on	O
leave	O
from	O
CMU	O
,	O
developed	O
the	O
Lycos	B-Application
search	O
engine	O
.	O
</s>
<s>
Finding	O
and	O
selecting	O
full	O
or	O
partial	O
content	O
based	O
on	O
the	B-Application
keywords	I-Application
provided	O
.	O
</s>
<s>
Allowing	O
users	O
to	O
look	O
for	O
words	O
or	O
combinations	O
of	O
words	O
found	O
in	O
that	O
index	B-Algorithm
.	O
</s>
<s>
The	O
process	O
begins	O
when	O
a	O
user	O
enters	O
a	O
query	B-Library
statement	O
into	O
the	O
system	O
through	O
the	O
interface	O
provided	O
.	O
</s>
<s>
Text-based	O
Google	B-Application
,	O
Bing	B-Application
,	O
Yahoo	B-Application
!	I-Application
</s>
<s>
Limited	O
search	O
using	O
queries	B-Library
in	O
natural	O
language	O
.	O
</s>
<s>
Voice-based	B-Application
Google	B-Application
,	O
Bing	B-Application
,	O
Yahoo	B-Application
!	I-Application
</s>
<s>
Limited	O
search	O
using	O
queries	B-Library
in	O
natural	O
language	O
.	O
</s>
<s>
Crawler-based	O
search	O
engines	O
are	O
those	O
that	O
use	O
automated	O
software	O
agents	O
(	O
called	O
crawlers	O
)	O
that	O
visit	O
a	O
Web	O
site	O
,	O
read	O
the	O
information	O
on	O
the	O
actual	O
site	O
,	O
read	O
the	O
site	O
's	O
meta	O
tags	O
and	O
also	O
follow	O
the	O
links	O
that	O
the	O
site	O
connects	O
to	O
performing	O
indexing	B-Application
on	O
all	O
linked	O
Web	O
sites	O
as	O
well	O
.	O
</s>
<s>
The	O
crawler	B-Application
returns	O
all	O
that	O
information	O
back	O
to	O
a	O
central	O
depository	O
,	O
where	O
the	O
data	O
is	O
indexed	B-Application
.	O
</s>
<s>
The	O
crawler	B-Application
will	O
periodically	O
return	O
to	O
the	O
sites	O
to	O
check	O
for	O
any	O
information	O
that	O
has	O
changed	O
.	O
</s>
<s>
Human-powered	O
search	O
engines	O
rely	O
on	O
humans	O
to	O
submit	O
information	O
that	O
is	O
subsequently	O
indexed	B-Application
and	O
catalogued	O
.	O
</s>
<s>
Only	O
information	O
that	O
is	O
submitted	O
is	O
put	O
into	O
the	O
index	B-Algorithm
.	O
</s>
<s>
In	O
both	O
cases	O
,	O
when	O
you	O
query	B-Library
a	O
search	O
engine	O
to	O
locate	O
information	O
,	O
you	O
're	O
actually	O
searching	O
through	O
the	O
index	B-Algorithm
that	O
the	O
search	O
engine	O
has	O
created	O
—	O
you	O
are	O
not	O
actually	O
searching	O
the	O
Web	O
.	O
</s>
<s>
This	O
explains	O
why	O
sometimes	O
a	O
search	O
on	O
a	O
commercial	O
search	O
engine	O
,	O
such	O
as	O
Yahoo	B-Application
!	I-Application
</s>
<s>
or	O
Google	B-Application
,	O
will	O
return	O
results	O
that	O
are	O
,	O
in	O
fact	O
,	O
dead	O
links	O
.	O
</s>
<s>
Since	O
the	O
search	O
results	O
are	O
based	O
on	O
the	O
index	B-Algorithm
,	O
if	O
the	O
index	B-Algorithm
has	O
not	O
been	O
updated	O
since	O
a	O
Web	O
page	O
became	O
invalid	O
the	O
search	O
engine	O
treats	O
the	O
page	O
as	O
still	O
an	O
active	O
link	O
even	O
though	O
it	O
no	O
longer	O
is	O
.	O
</s>
<s>
It	O
will	O
remain	O
that	O
way	O
until	O
the	O
index	B-Algorithm
is	O
updated	O
.	O
</s>
<s>
The	O
algorithm	O
is	O
what	O
the	O
search	O
engines	O
use	O
to	O
determine	O
the	O
relevance	O
of	O
the	O
information	O
in	O
the	O
index	B-Algorithm
to	O
what	O
the	O
user	O
is	O
searching	O
for	O
.	O
</s>
<s>
By	O
analyzing	O
how	O
pages	O
link	O
to	O
each	O
other	O
,	O
an	O
engine	O
can	O
both	O
determine	O
what	O
a	O
page	O
is	O
about	O
(	O
if	O
the	B-Application
keywords	I-Application
of	O
the	O
linked	O
pages	O
are	O
similar	O
to	O
the	B-Application
keywords	I-Application
on	O
the	O
original	O
page	O
)	O
and	O
whether	O
that	O
page	O
is	O
considered	O
"	O
important	O
"	O
and	O
deserving	O
of	O
a	O
boost	O
in	O
ranking	O
.	O
</s>
<s>
Google	B-Application
)	O
,	O
database	O
or	O
structured	O
data	O
search	O
engines	O
(	O
e.g.	O
</s>
<s>
The	O
more	O
prevalent	O
search	O
engines	O
,	O
such	O
as	O
Google	B-Application
and	O
Yahoo	O
!,	O
utilize	O
hundreds	O
of	O
thousands	O
computers	O
to	O
process	O
trillions	O
of	O
web	O
pages	O
in	O
order	O
to	O
return	O
fairly	O
well-aimed	O
results	O
.	O
</s>
<s>
Due	O
to	O
this	O
high	O
volume	O
of	O
queries	B-Library
and	O
text	O
processing	O
,	O
the	O
software	O
is	O
required	O
to	O
run	O
in	O
a	O
highly	O
dispersed	O
environment	O
with	O
a	O
high	O
degree	O
of	O
superfluity	O
.	O
</s>
