<s>
The	O
Public	B-Protocol
Suffix	I-Protocol
List	I-Protocol
(	O
PSL	O
)	O
is	O
a	O
catalog	O
of	O
certain	O
Internet	O
domain	O
names	O
.	O
</s>
<s>
Entries	O
on	O
the	O
list	O
are	O
also	O
referred	O
to	O
as	O
effective	B-Protocol
top-level	I-Protocol
domains	I-Protocol
(	O
eTLD	B-Protocol
)	O
.	O
</s>
<s>
The	B-Operating_System
Mozilla	I-Operating_System
Foundation	I-Operating_System
initiated	O
the	O
suffix	O
list	O
for	O
the	O
security	O
and	O
privacy	O
policies	O
of	O
its	O
Firefox	B-Application
web	I-Application
browser	I-Application
,	O
but	O
it	O
is	O
widely	O
applied	O
,	O
with	O
varying	O
success	O
,	O
to	O
a	O
variety	O
of	O
other	O
purposes	O
under	O
the	O
Mozilla	B-License
Public	I-License
License	I-License
(	O
MPL	O
)	O
.	O
</s>
<s>
The	O
list	O
is	O
used	O
by	O
Mozilla	B-Operating_System
browsers	O
(	O
Firefox	B-Application
)	O
,	O
by	O
Google	O
in	O
Chrome	B-Application
and	O
Chromium	B-Language
projects	I-Language
on	O
certain	O
platforms	O
,	O
and	O
by	O
Opera	B-Application
.	O
</s>
<s>
According	O
to	O
Mozilla	B-Operating_System
,	O
</s>
<s>
While	O
com	O
,	O
uk	O
,	O
and	O
us	O
are	O
top-level	O
domains	O
(	O
TLDs	O
)	O
,	O
Internet	O
users	O
cannot	O
always	O
register	O
the	O
next	O
level	O
of	O
domain	O
,	O
such	O
as	O
"	O
co.uk	O
 "	O
or	O
"	O
wy.us	O
 "	O
,	O
because	O
these	O
may	O
be	O
controlled	O
by	O
domain	B-Application
registrars	I-Application
.	O
</s>
<s>
The	O
Public	B-Protocol
Suffix	I-Protocol
List	I-Protocol
is	O
intended	O
to	O
enumerate	O
all	O
domain	O
suffixes	O
controlled	O
by	O
registrars	O
.	O
</s>
<s>
they	O
share	O
a	O
suffix	O
that	O
is	O
not	O
included	O
in	O
the	O
Public	B-Protocol
Suffix	I-Protocol
List	I-Protocol
.	O
</s>
<s>
Security	O
issues	O
like	O
a	O
same-site	O
attack	O
can	O
arise	O
if	O
the	O
Public	B-Protocol
Suffix	I-Protocol
List	I-Protocol
is	O
incorrect	O
,	O
or	O
if	O
browsers	O
or	O
sites	O
are	O
not	O
properly	O
configured	O
.	O
</s>
<s>
Highlighting	O
the	O
most	O
important	O
part	O
of	O
a	O
domain	O
name	O
in	O
the	O
user	B-Application
interface	I-Application
.	O
</s>
<s>
In	O
2021	O
,	O
privacy	O
enhancements	O
in	O
iOS	B-Application
14.5	O
related	O
to	O
Apple	O
's	O
Identifier	B-Operating_System
for	I-Operating_System
Advertisers	I-Operating_System
and	O
unclear	O
guidance	O
from	O
Facebook	O
led	O
to	O
a	O
flood	O
of	O
inappropriate	O
requests	O
for	O
domains	O
to	O
be	O
added	O
to	O
the	O
Public	B-Protocol
Suffix	I-Protocol
List	I-Protocol
.	O
</s>
