<s>
A	O
web	O
browser	O
is	O
an	O
application	B-Application
for	O
accessing	O
websites	O
.	O
</s>
<s>
When	O
a	O
user	O
requests	O
a	O
web	O
page	O
from	O
a	O
particular	O
website	O
,	O
the	O
browser	O
retrieves	O
its	O
files	B-Operating_System
from	O
a	O
web	B-Application
server	I-Application
and	O
then	O
displays	O
the	O
page	O
on	O
the	O
user	O
's	O
screen	O
.	O
</s>
<s>
Browsers	O
are	O
used	O
on	O
a	O
range	O
of	O
devices	O
,	O
including	O
desktops	B-Device
,	O
laptops	B-Device
,	O
tablets	B-Device
,	O
and	O
smartphones	B-Application
.	O
</s>
<s>
The	O
most	B-Application
used	I-Application
browser	O
is	O
Google	B-Application
Chrome	I-Application
,	O
with	O
a	O
65%	O
global	O
market	O
share	O
on	O
all	O
devices	O
,	O
followed	O
by	O
Safari	B-Application
with	O
18%	O
.	O
</s>
<s>
A	O
web	O
browser	O
is	O
not	O
the	O
same	O
thing	O
as	O
a	O
search	B-Application
engine	I-Application
,	O
though	O
the	O
two	O
are	O
often	O
confused	O
.	O
</s>
<s>
A	O
search	B-Application
engine	I-Application
is	O
a	O
website	O
that	O
provides	O
links	O
to	O
other	O
websites	O
.	O
</s>
<s>
This	O
process	O
begins	O
when	O
the	O
user	O
inputs	O
a	O
Uniform	O
Resource	O
Locator	O
(	O
URL	O
)	O
,	O
such	O
as	O
https://en.wikipedia.org/	O
,	O
into	O
the	O
browser	O
.	O
</s>
<s>
Virtually	O
all	O
URLs	O
are	O
retrieved	O
using	O
the	O
Hypertext	B-Protocol
Transfer	I-Protocol
Protocol	I-Protocol
(	O
HTTP	B-Protocol
)	O
,	O
a	O
set	O
of	O
rules	O
for	O
the	O
transfer	O
of	O
data	O
.	O
</s>
<s>
If	O
the	O
URL	O
uses	O
the	O
secure	B-Protocol
mode	I-Protocol
of	O
HTTP	B-Protocol
(	O
HTTPS	B-Protocol
)	O
,	O
the	O
connection	O
between	O
the	O
browser	O
and	O
the	O
web	B-Application
server	I-Application
is	O
encrypted	O
for	O
the	O
purposes	O
of	O
communications	O
security	O
and	O
information	O
privacy	O
.	O
</s>
<s>
Each	O
link	O
contains	O
a	O
URL	O
,	O
and	O
when	O
it	O
is	O
clicked	O
or	O
tapped	B-Device
,	O
the	O
browser	O
navigates	O
to	O
the	O
new	O
resource	O
.	O
</s>
<s>
Most	O
browsers	O
use	O
an	O
internal	O
cache	B-Protocol
of	O
web	O
page	O
resources	O
to	O
improve	O
loading	O
times	O
for	O
subsequent	O
visits	O
to	O
the	O
same	O
page	O
.	O
</s>
<s>
The	O
cache	B-Protocol
can	O
store	O
many	O
items	O
,	O
such	O
as	O
large	O
images	O
,	O
so	O
they	O
do	O
not	O
need	O
to	O
be	O
downloaded	O
from	O
the	O
server	O
again	O
.	O
</s>
<s>
Cached	O
items	O
are	O
usually	O
only	O
stored	O
for	O
as	O
long	O
as	O
the	O
web	B-Application
server	I-Application
stipulates	O
in	O
its	O
HTTP	B-Protocol
response	O
messages	O
.	O
</s>
<s>
During	O
the	O
course	O
of	O
browsing	O
,	O
cookies	B-Application
received	O
from	O
various	O
websites	O
are	O
stored	O
by	O
the	O
browser	O
.	O
</s>
<s>
However	O
,	O
others	O
are	O
used	O
for	O
tracking	O
user	O
behavior	O
over	O
long	O
periods	O
of	O
time	O
,	O
so	O
browsers	O
typically	O
provide	O
a	O
section	O
in	O
the	O
menu	O
for	O
deleting	O
cookies	B-Application
.	O
</s>
<s>
Finer-grained	O
management	O
of	O
cookies	B-Application
usually	O
requires	O
a	O
browser	B-Protocol
extension	I-Protocol
.	O
</s>
<s>
The	O
first	O
web	O
browser	O
,	O
called	O
WorldWideWeb	B-Language
,	O
was	O
created	O
in	O
1990	O
by	O
Sir	O
Tim	O
Berners-Lee	O
.	O
</s>
<s>
He	O
then	O
recruited	O
Nicola	O
Pellow	O
to	O
write	O
the	O
Line	B-Protocol
Mode	I-Protocol
Browser	I-Protocol
,	O
which	O
displayed	O
web	O
pages	O
on	O
dumb	O
terminals	O
.	O
</s>
<s>
The	O
Mosaic	B-Application
web	I-Application
browser	I-Application
was	O
released	O
in	O
April	O
1993	O
,	O
and	O
was	O
later	O
credited	O
as	O
the	O
first	O
web	O
browser	O
to	O
find	O
mainstream	O
popularity	O
.	O
</s>
<s>
Its	O
innovative	O
graphical	B-Application
user	I-Application
interface	I-Application
made	O
the	O
World	O
Wide	O
Web	O
easy	O
to	O
navigate	O
and	O
thus	O
more	O
accessible	O
to	O
the	O
average	O
person	O
.	O
</s>
<s>
Marc	O
Andreessen	O
,	O
the	O
leader	O
of	O
the	O
Mosaic	B-Application
team	O
,	O
started	O
his	O
own	O
company	O
,	O
Netscape	B-Protocol
,	O
which	O
released	O
the	O
Mosaic-influenced	O
Netscape	B-Protocol
Navigator	I-Protocol
in	O
1994	O
.	O
</s>
<s>
Microsoft	O
debuted	O
Internet	B-Application
Explorer	I-Application
in	O
1995	O
,	O
leading	O
to	O
a	O
browser	B-Application
war	I-Application
with	O
Netscape	B-Protocol
.	O
</s>
<s>
Within	O
a	O
few	O
years	O
,	O
Microsoft	O
gained	O
a	O
dominant	O
position	O
in	O
the	O
browser	O
market	O
for	O
two	O
reasons	O
:	O
it	O
bundled	O
Internet	B-Application
Explorer	I-Application
with	O
Microsoft	B-Application
Windows	I-Application
,	O
their	O
popular	O
operating	B-General_Concept
system	I-General_Concept
and	O
did	O
so	O
as	O
freeware	B-License
with	O
no	O
restrictions	O
on	O
usage	O
.	O
</s>
<s>
The	O
market	O
share	O
of	O
Internet	B-Application
Explorer	I-Application
peaked	O
at	O
over	O
95%	O
in	O
the	O
early	O
2000s	O
.	O
</s>
<s>
In	O
1998	O
,	O
Netscape	B-Protocol
launched	O
what	O
would	O
become	O
the	B-Operating_System
Mozilla	I-Operating_System
Foundation	I-Operating_System
to	O
create	O
a	O
new	O
browser	O
using	O
the	O
open-source	B-Application
software	I-Application
model	O
.	O
</s>
<s>
This	O
work	O
evolved	O
into	O
the	O
Firefox	B-Application
browser	I-Application
,	O
first	O
released	O
by	O
Mozilla	O
in	O
2004	O
.	O
</s>
<s>
Firefox	B-Application
's	O
market	O
share	O
peaked	O
at	O
32%	O
in	O
2010	O
.	O
</s>
<s>
Apple	O
released	O
its	O
Safari	B-Application
browser	I-Application
in	O
2003	O
.	O
</s>
<s>
Safari	B-Application
remains	O
the	O
dominant	O
browser	O
on	O
Apple	O
devices	O
,	O
though	O
it	O
did	O
not	O
become	O
popular	O
elsewhere	O
.	O
</s>
<s>
Google	B-Application
debuted	O
its	O
Chrome	B-Application
browser	I-Application
in	O
2008	O
,	O
which	O
steadily	O
took	O
market	O
share	O
from	O
Internet	B-Application
Explorer	I-Application
and	O
became	O
the	O
most	O
popular	O
browser	O
in	O
2012	O
.	O
</s>
<s>
Chrome	B-Operating_System
has	O
remained	B-Application
dominant	I-Application
ever	O
since	O
.	O
</s>
<s>
By	O
2015	O
,	O
Microsoft	O
replaced	O
Internet	B-Application
Explorer	I-Application
with	O
Edge	B-Application
for	O
the	O
Windows	B-Operating_System
10	I-Operating_System
release	O
.	O
</s>
<s>
Since	O
the	O
early	O
2000s	O
,	O
browsers	O
have	O
greatly	O
expanded	O
their	O
HTML	B-Language
,	O
CSS	B-Language
,	O
JavaScript	B-Language
,	O
and	O
multimedia	O
capabilities	O
.	O
</s>
<s>
One	O
reason	O
has	O
been	O
to	O
enable	O
more	O
sophisticated	O
websites	O
,	O
such	O
as	O
web	B-Application
apps	I-Application
.	O
</s>
<s>
Another	O
factor	O
is	O
the	O
significant	O
increase	O
of	O
broadband	B-General_Concept
connectivity	O
,	O
which	O
enables	O
people	O
to	O
access	O
data-intensive	O
content	O
,	O
such	O
as	O
video	O
streaming	O
,	O
that	O
was	O
not	O
possible	O
during	O
the	O
era	O
of	O
dial-up	O
modems	O
.	O
</s>
<s>
The	O
current	O
most	B-Application
used	I-Application
browser	O
worldwide	O
is	O
Google	B-Application
Chrome	I-Application
,	O
with	O
a	O
65%	O
global	O
market	O
share	O
on	O
all	O
devices	O
.	O
</s>
<s>
Google	B-Application
Chrome	I-Application
is	O
built	O
on	O
Google	B-Application
's	I-Application
free	B-License
and	I-License
open-source	I-License
software	I-License
project	O
Chromium	B-Language
,	O
and	O
is	O
a	O
major	O
component	O
of	O
Google	B-Application
's	I-Application
operating	B-General_Concept
system	I-General_Concept
ChromeOS	B-Operating_System
.	O
</s>
<s>
Apple	B-Application
's	I-Application
Safari	I-Application
has	O
the	O
second	O
highest	O
global	O
market	O
share	O
,	O
at	O
18%	O
,	O
while	O
Microsoft	B-Application
Edge	I-Application
has	O
the	O
second	O
highest	O
desktop	B-Device
share	O
.	O
</s>
<s>
Safari	B-Application
is	O
based	O
on	O
WebKit	B-Language
and	O
is	O
the	O
default	O
web	O
browser	O
for	O
Mac	B-Device
computers	I-Device
.	O
</s>
<s>
Introduced	O
in	O
2015	O
,	O
Microsoft	B-Application
Edge	I-Application
is	O
the	O
default	O
web	O
browser	O
on	O
Windows	B-Operating_System
10	I-Operating_System
and	O
11	B-Application
computers	O
.	O
</s>
<s>
Mozilla	B-Operating_System
Foundation	I-Operating_System
's	O
Firefox	B-Application
is	O
the	O
fourth	O
most	O
popular	O
desktop	B-Device
browser	O
,	O
and	O
unlike	O
some	O
more	O
popular	O
browsers	O
,	O
is	O
free	B-License
and	I-License
open-source	I-License
.	O
</s>
<s>
Examples	O
include	O
Brave	B-Application
,	O
Epic	B-Protocol
,	O
Maxthon	B-Application
,	O
and	O
Opera	B-Application
.	O
</s>
<s>
The	O
Tor	B-Operating_System
Browser	I-Operating_System
gives	O
access	O
to	O
the	O
Tor	B-Application
anonymity	I-Application
network	I-Application
.	O
</s>
<s>
Tor	B-Application
allows	O
access	O
to	O
the	O
dark	O
web	O
,	O
repeatedly	O
encrypting	O
traffic	O
for	O
privacy	O
.	O
</s>
<s>
The	O
alternative	O
browsers	O
have	O
low	O
market	O
share	O
compared	O
to	O
the	O
large	O
browsers	O
;	O
for	O
example	O
,	O
Opera	B-Application
is	I-Application
the	O
highest	O
alternative	O
browser	O
by	O
a	O
wide	O
margin	O
,	O
at	O
a	O
2.49	O
%	O
market	O
share	O
in	O
October	O
2022	O
.	O
</s>
<s>
The	O
most	O
popular	O
browsers	O
share	O
many	O
features	B-Architecture
in	O
common	O
.	O
</s>
<s>
They	O
automatically	O
log	O
users	O
 '	O
browsing	B-Protocol
history	I-Protocol
,	O
unless	O
the	O
users	O
turn	O
off	O
their	O
browsing	B-Protocol
history	I-Protocol
or	O
use	O
the	O
non-logging	O
private	B-Protocol
mode	I-Protocol
.	O
</s>
<s>
They	O
also	O
allow	O
users	O
to	O
set	O
bookmarks	O
,	O
customize	O
the	O
browser	O
with	O
extensions	B-Protocol
,	O
and	O
can	O
manage	O
user	O
passwords	O
.	O
</s>
<s>
Some	O
provide	O
a	O
sync	O
service	O
and	O
web	O
accessibility	O
features	B-Architecture
.	O
</s>
<s>
Most	O
browsers	O
have	O
common	O
user	B-Application
interface	I-Application
features	B-Architecture
such	O
as	O
:	O
</s>
<s>
An	O
address	O
bar	O
to	O
input	O
the	O
URL	O
of	O
a	O
page	O
and	O
display	O
it	O
,	O
and	O
a	O
search	O
bar	O
to	O
input	O
terms	O
into	O
a	O
search	B-Application
engine	I-Application
.	O
</s>
<s>
While	O
mobile	B-Application
browsers	I-Application
have	O
similar	O
UI	O
features	B-Architecture
as	O
desktop	B-Device
versions	O
,	O
the	O
limitations	O
of	O
touch	B-Device
screens	I-Device
require	O
mobile	O
UIs	O
to	O
be	O
simpler	O
.	O
</s>
<s>
The	O
most	O
popular	O
desktop	B-Device
browsers	O
also	O
have	O
sophisticated	O
web	B-Application
development	I-Application
tools	I-Application
,	O
which	O
allows	O
developers	O
to	O
inspect	O
the	O
webpage	O
operations	O
.	O
</s>
<s>
Web	O
browsers	O
are	O
popular	O
targets	O
for	O
hackers	B-Application
,	O
who	O
exploit	O
security	O
holes	O
to	O
steal	O
information	O
,	O
destroy	O
files	B-Operating_System
,	O
and	O
other	O
malicious	O
activities	O
.	O
</s>
<s>
Other	O
protection	O
measures	O
are	O
antivirus	B-Application
software	I-Application
and	O
avoiding	O
known-malicious	O
websites	O
.	O
</s>
<s>
Breaches	O
of	O
web	O
browser	O
security	O
are	O
usually	O
for	O
the	O
purpose	O
of	O
bypassing	O
protections	O
to	O
display	O
pop-up	O
advertising	O
collecting	O
personally	O
identifiable	O
information	O
(	O
PII	O
)	O
for	O
either	O
Internet	O
marketing	O
or	O
identity	O
theft	O
,	O
website	O
tracking	O
or	O
web	O
analytics	O
about	O
a	O
user	O
against	O
their	O
will	O
using	O
tools	O
such	O
as	O
web	B-Protocol
bugs	I-Protocol
,	O
Clickjacking	O
,	O
Likejacking	O
(	O
where	O
Facebook	B-Application
's	O
like	O
button	O
is	O
targeted	O
)	O
,	O
HTTP	B-Application
cookies	I-Application
,	O
zombie	B-Application
cookies	I-Application
or	O
Flash	B-Operating_System
cookies	I-Operating_System
(	O
Local	B-Operating_System
Shared	I-Operating_System
Objects	I-Operating_System
or	O
LSOs	O
)	O
;	O
installing	O
adware	O
,	O
viruses	O
,	O
spyware	O
such	O
as	O
Trojan	O
horses	O
(	O
to	O
gain	O
access	O
to	O
users	O
 '	O
personal	B-Device
computers	I-Device
via	O
cracking	O
)	O
or	O
other	O
malware	O
including	O
online	B-Application
banking	I-Application
theft	O
using	O
man-in-the-browser	B-Protocol
attacks	O
.	O
</s>
