<s>
uBlock	B-Protocol
Origin	I-Protocol
(	O
;	O
""	O
)	O
is	O
a	O
free	B-License
and	I-License
open-source	I-License
browser	B-Protocol
extension	I-Protocol
for	O
content	B-Protocol
filtering	I-Protocol
,	O
including	O
ad	O
blocking	O
.	O
</s>
<s>
The	O
extension	O
is	O
available	O
for	O
Chrome	B-Application
,	O
Chromium	B-Language
,	O
Edge	B-Application
,	O
Firefox	B-Application
,	O
Opera	B-Application
,	O
Pale	B-Protocol
Moon	I-Protocol
,	O
as	O
well	O
as	O
versions	O
of	O
Safari	B-Application
prior	O
to	O
13	O
.	O
uBlock	B-Protocol
Origin	I-Protocol
has	O
received	O
praise	O
from	O
technology	O
websites	O
and	O
is	O
reported	O
to	O
be	O
much	O
less	O
memory-intensive	O
than	O
other	O
extensions	O
with	O
similar	O
functionality	O
.	O
</s>
<s>
uBlock	B-Protocol
Origin	I-Protocol
's	O
stated	O
purpose	O
is	O
to	O
give	O
users	O
the	O
means	O
to	O
enforce	O
their	O
own	O
(	O
content-filtering	O
)	O
choices	O
.	O
</s>
<s>
uBlock	B-Protocol
Origin	I-Protocol
is	O
actively	O
developed	O
and	O
maintained	O
by	O
its	O
creator	O
and	O
lead	O
developer	O
Raymond	O
Hill	O
.	O
</s>
<s>
uBlock	B-Protocol
was	O
initially	O
named	O
"	O
μBlock	O
"	O
but	O
the	O
name	O
was	O
later	O
changed	O
to	O
"	O
uBlock	B-Protocol
"	O
to	O
avoid	O
confusion	O
as	O
to	O
how	O
the	O
Greek	O
letter	O
μ	O
(	O
Mu/Micro	O
)	O
in	O
"	O
μBlock	O
"	O
should	O
be	O
pronounced	O
.	O
</s>
<s>
Development	O
started	O
by	O
forking	B-Application
from	O
the	O
codebase	B-General_Concept
of	O
HTTP	B-Operating_System
Switchboard	I-Operating_System
along	O
with	O
another	O
blocking	O
extension	O
called	O
uMatrix	O
,	O
designed	O
for	O
advanced	O
users	O
.	O
</s>
<s>
uBlock	B-Protocol
was	O
developed	O
by	O
Raymond	O
Hill	O
to	O
use	O
community-maintained	O
block	O
lists	O
,	O
while	O
adding	O
features	O
and	O
raising	O
the	O
code	O
quality	O
to	O
release	O
standards	O
.	O
</s>
<s>
First	O
released	O
in	O
June	O
2014	O
as	O
a	O
Chrome	B-Application
and	O
Opera	B-Application
extension	O
,	O
by	O
winter	O
2015	O
,	O
the	O
extension	O
had	O
expanded	O
to	O
other	O
browsers	O
.	O
</s>
<s>
The	O
uBlock	B-Protocol
project	O
official	O
repository	O
was	O
transferred	O
to	O
Chris	O
Aljoudi	O
by	O
original	O
developer	O
Raymond	O
Hill	O
in	O
April	O
2015	O
,	O
due	O
to	O
frustration	O
of	O
dealing	O
with	O
requests	O
.	O
</s>
<s>
This	O
version	O
was	O
later	O
renamed	O
uBlock	B-Protocol
Origin	I-Protocol
and	O
it	O
has	O
been	O
completely	O
divorced	O
from	O
Aljoudi	O
's	O
uBlock	B-Protocol
.	O
</s>
<s>
Aljoudi	O
created	O
ublock.org	O
to	O
host	O
and	O
promote	O
uBlock	B-Protocol
and	O
to	O
request	O
donations	O
.	O
</s>
<s>
In	O
response	O
,	O
uBlock	B-Protocol
's	O
founder	O
Raymond	O
Hill	O
stated	O
that	O
"	O
the	O
donations	O
sought	O
by	O
ublock.org	O
are	O
not	O
benefiting	O
any	O
of	O
those	O
who	O
contributed	O
most	O
to	O
create	O
uBlock	B-Protocol
Origin.	O
"	O
</s>
<s>
The	O
development	O
of	O
uBlock	B-Protocol
stopped	O
in	O
August	O
2015	O
and	O
it	O
has	O
been	O
sporadically	O
updated	O
since	O
January	O
2017	O
.	O
</s>
<s>
In	O
July	O
2018	O
,	O
ublock.org	O
was	O
acquired	O
by	O
AdBlock	B-Operating_System
,	O
and	O
since	O
February	O
2019	O
,	O
uBlock	B-Protocol
began	O
allowing	O
users	O
to	O
participate	O
in	O
"	O
Acceptable	B-Application
Ads	I-Application
"	O
,	O
a	O
program	O
run	O
by	O
Adblock	B-Application
Plus	I-Application
that	O
allows	O
some	O
ads	O
which	O
are	O
deemed	O
"	O
acceptable	O
"	O
,	O
and	O
for	O
which	O
the	O
larger	O
publishers	O
pay	O
a	O
fee	O
.	O
</s>
<s>
uBlock	B-Protocol
Origin	I-Protocol
remains	O
independent	O
and	O
does	O
not	O
allow	O
ads	O
for	O
payment	O
.	O
</s>
<s>
Raymond	O
Hill	O
,	O
the	O
founder	O
and	O
original	O
author	O
of	O
uBlock	B-Protocol
,	O
,	O
continued	O
to	O
work	O
on	O
the	O
extension	O
under	O
the	O
name	O
uBlock	B-Protocol
Origin	I-Protocol
,	O
sometimes	O
stylized	O
as	O
uBlock0	O
,	O
and	O
abbreviated	O
as	O
uBO	O
.	O
</s>
<s>
In	O
January	O
2016	O
,	O
uBlock	B-Protocol
Origin	I-Protocol
was	O
added	O
to	O
the	O
repositories	O
for	O
Debian	O
9	O
and	O
Ubuntu	B-Operating_System
16.04	O
.	O
</s>
<s>
The	O
extension	O
was	O
awarded	O
"	O
Pick	O
of	O
the	O
Month	O
"	O
by	O
Mozilla	B-Operating_System
for	O
May	O
2016	O
.	O
</s>
<s>
On	O
December	O
11	O
,	O
2016	O
,	O
Nik	O
Rolls	O
released	O
a	O
fork	B-Application
of	O
uBlock	B-Protocol
Origin	I-Protocol
for	O
the	O
Microsoft	B-Application
Edge	I-Application
browser	O
(	O
now	O
known	O
as	O
Microsoft	B-Application
Edge	I-Application
Legacy	O
)	O
.	O
</s>
<s>
In	O
April	O
2020	O
,	O
this	O
fork	B-Application
was	O
deprecated	O
as	O
Microsoft	O
replaced	O
Microsoft	B-Application
Edge	I-Application
Legacy	O
with	O
a	O
Chromium-based	O
Edge	B-Application
.	O
</s>
<s>
,	O
the	O
uBlock	B-Protocol
Origin	I-Protocol
Chrome	B-Application
extension	O
had	O
over	O
10	O
million	O
active	O
users	O
and	O
the	O
Firefox	B-Application
version	O
had	O
5	O
million	O
active	O
users	O
.	O
</s>
<s>
uBlock	B-Protocol
Origin	I-Protocol
supports	O
the	O
majority	O
of	O
Adblock	B-Application
Plus	I-Application
's	O
filter	O
syntax	O
.	O
</s>
<s>
The	O
extensions	O
are	O
capable	O
of	O
importing	O
hosts	B-Protocol
files	I-Protocol
and	O
a	O
number	O
of	O
community-maintained	O
lists	O
are	O
available	O
at	O
installation	O
.	O
</s>
<s>
Among	O
the	O
host	B-Protocol
files	I-Protocol
available	O
,	O
Peter	O
Lowe	O
's	O
ad	O
servers	O
&	O
tracking	O
list	O
and	O
lists	O
of	O
malware	O
domains	O
are	O
also	O
enabled	O
as	O
default	O
.	O
</s>
<s>
uBlock	B-Protocol
Origin	I-Protocol
includes	O
a	O
growing	O
list	O
of	O
features	O
not	O
available	O
in	O
uBlock	B-Protocol
,	O
including	O
:	O
</s>
<s>
Interface	O
enhancements	O
including	O
a	O
DOM	B-General_Concept
inspector	O
,	O
privacy-oriented	O
options	O
to	O
block	O
link	B-Protocol
prefetching	I-Protocol
,	O
hyperlink	O
auditing	O
,	O
and	O
IP	O
address	O
leaks	O
via	O
WebRTC	B-Protocol
(	O
uBO-Extra	O
is	O
required	O
to	O
block	O
WebRTC	B-Protocol
connections	O
in	O
Chromium	B-Language
)	O
.	O
</s>
<s>
Site-specific	O
switches	O
to	O
toggle	O
the	O
blocking	O
of	O
pop-ups	O
,	O
strict	O
domain	O
blocking	O
,	O
cosmetic	O
filtering	O
,	O
blocking	O
remote	O
fonts	O
,	O
and	O
JavaScript	B-Language
disabling	O
were	O
also	O
added	O
to	O
uBlock	B-Protocol
Origin	I-Protocol
.	O
</s>
<s>
The	O
Firefox	B-Application
version	O
of	O
uBlock	B-Protocol
Origin	I-Protocol
has	O
an	O
extra	O
feature	O
which	O
helps	O
to	O
foil	O
attempts	O
by	O
web	O
sites	O
to	O
circumvent	O
blockers	O
.	O
</s>
<s>
In	O
November	O
2019	O
,	O
a	O
uBlock	B-Protocol
Origin	I-Protocol
user	O
reported	O
a	O
novel	O
technique	O
used	O
by	O
some	O
sites	O
to	O
bypass	O
third-party	O
tracker	O
blocking	O
.	O
</s>
<s>
These	O
sites	O
link	O
to	O
URLs	O
that	O
are	O
sub-domains	O
of	O
the	O
page	O
's	O
domain	O
,	O
but	O
those	O
sub-domains	O
resolve	O
to	O
third-party	O
hosts	B-Protocol
via	O
a	O
CNAME	B-Protocol
record	I-Protocol
.	O
</s>
<s>
Since	O
the	O
initial	O
URL	O
contained	O
a	O
sub-domain	O
of	O
the	O
current	O
page	O
,	O
it	O
was	O
interpreted	O
by	O
browsers	O
as	O
a	O
first-party	O
request	O
and	O
so	O
was	O
allowed	O
by	O
the	O
filtering	O
rules	O
in	O
uBlock	B-Protocol
Origin	I-Protocol
(	O
and	O
in	O
similar	O
extensions	O
)	O
.	O
</s>
<s>
The	O
uBlock	B-Protocol
Origin	I-Protocol
developer	O
came	O
up	O
with	O
a	O
solution	O
using	O
a	O
DNS	O
API	O
which	O
is	O
exclusive	O
to	O
Firefox	B-Application
60+	O
.	O
</s>
<s>
The	O
new	O
feature	O
was	O
implemented	O
in	O
uBlock	B-Protocol
Origin	I-Protocol
1.25	O
,	O
released	O
on	O
February	O
19	O
,	O
2020	O
.	O
</s>
<s>
Technology	O
websites	O
and	O
user	O
reviews	O
for	O
uBlock	B-Protocol
Origin	I-Protocol
have	O
regarded	O
the	O
extension	O
as	O
less	O
resource-intensive	O
than	O
extensions	O
that	O
provide	O
similar	O
feature	O
sets	O
such	O
as	O
Adblock	B-Application
Plus	I-Application
.	O
</s>
<s>
A	O
benchmark	O
test	O
,	O
conducted	O
in	O
August	O
2015	O
with	O
ten	O
blocking	O
extensions	O
,	O
showed	O
uBlock	B-Protocol
Origin	I-Protocol
as	O
the	O
most	O
resource-efficient	O
among	O
the	O
extensions	O
tested	O
.	O
</s>
<s>
uBlock	B-Protocol
Origin	I-Protocol
surveys	O
what	O
style	O
resources	O
are	O
required	O
for	O
an	O
individual	O
web	O
page	O
rather	O
than	O
relying	O
on	O
a	O
universal	O
style	O
sheet	O
.	O
</s>
<s>
The	O
extension	O
takes	O
a	O
snapshot	B-Application
of	O
the	O
filters	O
the	O
user	O
has	O
enabled	O
,	O
which	O
contributes	O
to	O
accelerated	O
browser	O
start-up	O
speed	O
when	O
compared	O
to	O
retrieving	O
filters	O
from	O
cache	O
every	O
time	O
.	O
</s>
<s>
uBlock	B-Protocol
Origin	I-Protocol
is	O
actively	O
developed	O
for	O
applications	O
based	O
on	O
two	O
major	O
layout	O
engines	O
.	O
</s>
<s>
Safari	B-Application
(	O
desktop	O
:	O
uBlock	B-Protocol
Origin	I-Protocol
1.10.0	O
and	O
later	O
(	O
Beta	O
)	O
)	O
.	O
</s>
<s>
Stopped	O
working	O
with	O
macOS	O
10.15	O
Catalina	O
and	O
Safari	B-Application
13	O
.	O
</s>
<s>
Microsoft	B-Application
Edge	I-Application
(	O
legacy	O
)	O
(	O
uBlock	B-Protocol
Origin	I-Protocol
is	O
available	O
on	O
the	O
Windows	B-Application
Store	I-Application
in	O
beta	O
from	O
1.10.0	O
)	O
.	O
</s>
