<s>
A	O
web	B-Application
directory	I-Application
or	O
link	B-Application
directory	I-Application
is	O
an	O
online	O
list	O
or	O
catalog	O
of	O
websites	O
.	O
</s>
<s>
A	O
web	B-Application
directory	I-Application
includes	O
entries	O
about	O
websites	O
,	O
including	O
links	O
to	O
those	O
websites	O
,	O
organized	O
into	O
categories	O
and	O
subcategories	O
.	O
</s>
<s>
In	O
most	O
web	B-Application
directories	I-Application
,	O
the	O
entries	O
are	O
about	O
whole	O
websites	O
,	O
rather	O
than	O
individual	O
pages	O
within	O
them	O
(	O
called	O
"	O
deep	O
links	O
"	O
)	O
.	O
</s>
<s>
There	O
are	O
two	O
ways	O
to	O
find	O
information	O
on	O
the	O
Web	O
:	O
by	O
searching	B-Application
or	O
browsing	O
.	O
</s>
<s>
Web	B-Application
directories	I-Application
provide	O
links	O
in	O
a	O
structured	O
list	O
to	O
make	O
browsing	O
easier	O
.	O
</s>
<s>
Many	O
web	B-Application
directories	I-Application
combine	O
searching	B-Application
and	O
browsing	O
by	O
providing	O
a	O
search	B-Application
engine	I-Application
to	O
search	O
the	O
directory	O
.	O
</s>
<s>
Unlike	O
search	B-Application
engines	I-Application
,	O
which	O
base	O
results	O
on	O
a	O
database	O
of	O
entries	O
gathered	O
automatically	O
by	O
web	B-Application
crawler	I-Application
,	O
most	O
web	B-Application
directories	I-Application
are	O
built	O
manually	O
by	O
human	O
editors	O
.	O
</s>
<s>
Many	O
web	B-Application
directories	I-Application
allow	O
site	O
owners	O
to	O
submit	O
their	O
site	O
for	O
inclusion	O
,	O
and	O
have	O
editors	O
review	O
submissions	O
for	O
fitness	O
.	O
</s>
<s>
Web	B-Application
directories	I-Application
may	O
be	O
general	O
in	O
scope	O
,	O
or	O
limited	O
to	O
particular	O
subjects	O
or	O
fields	O
.	O
</s>
<s>
RSS	O
directories	O
are	O
similar	O
to	O
web	B-Application
directories	I-Application
,	O
but	O
contain	O
collections	O
of	O
RSS	O
feeds	O
,	O
instead	O
of	O
links	O
to	O
web	O
sites	O
.	O
</s>
<s>
During	O
the	O
early	O
development	O
of	O
the	O
web	O
,	O
there	O
was	O
a	O
list	O
of	O
web	B-Application
servers	I-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>
He	O
also	O
created	O
the	O
World	B-Application
Wide	I-Application
Web	I-Application
Virtual	I-Application
Library	I-Application
,	O
which	O
is	O
the	O
oldest	O
web	B-Application
directory	I-Application
.	O
</s>
<s>
One	O
type	O
of	O
niche	O
directory	O
with	O
a	O
large	O
number	O
of	O
sites	O
in	O
existence	O
is	O
the	O
shopping	B-Application
directory	I-Application
.	O
</s>
<s>
Shopping	B-Application
directories	I-Application
specialize	O
in	O
the	O
listing	O
of	O
retail	O
e-commerce	O
sites	O
.	O
</s>
<s>
Examples	O
of	O
well-known	O
general	O
web	B-Application
directories	I-Application
are	O
Yahoo	O
!	O
</s>
<s>
Directory	O
(	O
shut	O
down	O
at	O
the	O
end	O
of	O
2014	O
)	O
and	O
DMOZ	B-Application
(	O
shut	O
down	O
on	O
March	O
14	O
,	O
2017	O
)	O
.	O
</s>
<s>
DMOZ	B-Application
was	O
significant	O
due	O
to	O
its	O
extensive	O
categorization	O
and	O
large	O
number	O
of	O
listings	O
and	O
its	O
free	O
availability	O
for	O
use	O
by	O
other	O
directories	O
and	O
search	B-Application
engines	I-Application
.	O
</s>
<s>
However	O
,	O
a	O
debate	O
over	O
the	O
quality	O
of	O
directories	O
and	O
databases	O
still	O
continues	O
,	O
as	O
search	B-Application
engines	I-Application
use	O
ODP	O
's	O
content	O
without	O
real	O
integration	O
,	O
and	O
some	O
experiment	O
using	O
clustering	B-Algorithm
.	O
</s>
<s>
There	O
have	O
been	O
many	O
attempts	O
to	O
make	O
building	O
web	B-Application
directories	I-Application
easier	O
,	O
such	O
as	O
using	O
automated	O
submission	O
of	O
related	O
links	O
by	O
script	O
,	O
or	O
any	O
number	O
of	O
available	O
PHP	B-Application
portals	O
and	O
programs	O
.	O
</s>
<s>
Recently	O
,	O
social	O
software	O
techniques	O
have	O
spawned	O
new	O
efforts	O
of	O
categorization	O
,	O
with	O
Amazon.com	B-Application
adding	O
tagging	B-General_Concept
to	O
their	O
product	O
pages	O
.	O
</s>
<s>
Human-edited	B-Application
directories	I-Application
are	O
often	O
targeted	O
by	O
SEOs	O
on	O
the	O
basis	O
that	O
links	O
from	O
reputable	O
sources	O
will	O
improve	O
rankings	O
in	O
the	O
major	O
search	B-Application
engines	I-Application
.	O
</s>
<s>
Some	O
directories	O
may	O
prevent	O
search	B-Application
engines	I-Application
from	O
rating	O
a	O
displayed	O
link	O
by	O
using	O
redirects	O
,	O
nofollow	B-Application
attributes	O
,	O
or	O
other	O
techniques	O
.	O
</s>
<s>
Many	O
human-edited	B-Application
directories	I-Application
,	O
including	O
DMOZ	B-Application
,	O
World	B-Application
Wide	I-Application
Web	I-Application
Virtual	I-Application
Library	I-Application
,	O
Business.com	B-Application
and	O
Jasmine	O
Directory	O
,	O
are	O
edited	O
by	O
volunteers	O
,	O
who	O
are	O
often	O
experts	O
in	O
particular	O
categories	O
.	O
</s>
<s>
In	O
response	O
to	O
these	O
criticisms	O
,	O
some	O
volunteer-edited	O
directories	O
have	O
adopted	O
wiki	B-Protocol
technology	O
,	O
to	O
allow	O
broader	O
community	O
participation	O
in	O
editing	O
the	O
directory	O
(	O
at	O
the	O
risk	O
of	O
introducing	O
lower-quality	O
,	O
less	O
objective	O
entries	O
)	O
.	O
</s>
<s>
Another	O
direction	O
taken	O
by	O
some	O
web	B-Application
directories	I-Application
is	O
the	O
paid	O
for	O
inclusion	O
model	O
.	O
</s>
<s>
Today	O
submission	O
of	O
websites	O
to	O
web	B-Application
directories	I-Application
is	O
considered	O
a	O
common	O
SEO	O
(	O
search	B-Application
engine	I-Application
optimization	O
)	O
technique	O
to	O
get	O
back-links	O
for	O
the	O
submitted	O
website	O
.	O
</s>
<s>
One	O
distinctive	O
feature	O
of	O
'	O
directory	O
submission	O
 '	O
is	O
that	O
it	O
cannot	O
be	O
fully	O
automated	O
like	O
search	B-Application
engine	I-Application
submissions	O
.	O
</s>
<s>
Bid	O
for	O
Position	O
directories	O
,	O
also	O
known	O
as	O
bidding	O
web	B-Application
directories	I-Application
,	O
are	O
paid-for-inclusion	O
web	B-Application
directories	I-Application
where	O
the	O
listings	O
of	O
websites	O
in	O
the	O
directory	O
are	O
ordered	O
according	O
to	O
their	O
bid	O
amount	O
.	O
</s>
<s>
They	O
are	O
special	O
in	O
that	O
the	O
more	O
a	O
person	O
pays	O
,	O
the	O
higher	O
up	O
the	O
list	B-Architecture
of	I-Architecture
websites	I-Architecture
in	O
the	O
directory	O
they	O
go	O
.	O
</s>
<s>
Web	B-Application
directories	I-Application
will	O
often	O
make	O
themselves	O
accessing	O
by	O
more	O
and	O
more	O
URLs	O
by	O
acquiring	O
the	O
domain	O
registrations	O
of	O
defunct	O
websites	O
as	O
soon	O
as	O
they	O
expire	O
,	O
a	O
practice	O
known	O
as	O
Domain	O
drop	O
catching	O
.	O
</s>
