<s>
A	O
validator	B-Application
is	O
a	O
computer	B-Application
program	I-Application
used	O
to	O
check	O
the	O
validity	O
or	O
syntactical	O
correctness	O
of	O
a	O
fragment	O
of	O
code	O
or	O
document	O
.	O
</s>
<s>
The	O
term	O
is	O
commonly	O
used	O
in	O
the	O
context	O
of	O
validating	O
HTML	B-Language
,	O
CSS	B-Language
,	O
and	O
XML	B-Protocol
documents	I-Protocol
like	O
RSS	O
feeds	O
,	O
though	O
it	O
can	O
be	O
used	O
for	O
any	O
defined	O
format	O
or	O
language	O
.	O
</s>
<s>
Accessibility	O
validators	B-Application
are	O
automated	O
tools	O
that	O
are	O
designed	O
to	O
verify	O
compliance	O
of	O
a	O
web	O
page	O
or	O
a	O
web	O
site	O
with	O
respect	O
to	O
one	O
or	O
more	O
accessibility	O
guidelines	O
(	O
such	O
as	O
WCAG	O
,	O
Section	O
508	O
or	O
those	O
associated	O
with	O
national	O
laws	O
such	O
as	O
the	O
Stanca	O
Act	O
)	O
.	O
</s>
