<s>
Internet	B-Application
Explorer	I-Application
Developer	I-Application
Tools	I-Application
,	O
also	O
known	O
as	O
the	O
F12	B-Application
Developer	I-Application
Tools	I-Application
in	O
Windows	O
10	O
,	O
formerly	O
known	O
as	O
Internet	B-Application
Explorer	I-Application
Developer	I-Application
Toolbar	I-Application
,	O
is	O
a	O
web	B-Application
development	I-Application
tool	I-Application
built	O
into	O
Microsoft	B-Application
Internet	I-Application
Explorer	I-Application
and	O
Microsoft	B-Application
Edge	I-Application
that	O
aids	O
in	O
the	O
design	O
and	O
debugging	O
of	O
web	O
pages	O
.	O
</s>
<s>
It	O
was	O
introduced	O
as	O
a	O
toolbar	O
for	O
Internet	B-Application
Explorer	I-Application
6	I-Application
and	O
7	B-Application
.	O
</s>
<s>
Internet	B-Application
Explorer	I-Application
8	I-Application
and	O
later	O
have	O
developer	O
tools	O
built	O
in	O
.	O
</s>
<s>
It	O
allows	O
validating	O
of	O
CSS	B-Language
and	O
HTML	B-Language
,	O
previewing	O
page	O
layout	O
at	O
various	O
resolutions	O
,	O
and	O
also	O
offers	O
a	O
ruler	O
(	O
measuring	O
in	O
pixels	O
)	O
to	O
aid	O
in	O
positioning	O
the	O
elements	O
.	O
</s>
<s>
It	O
allows	O
viewing	O
the	O
source	O
of	O
the	O
entire	O
page	O
,	O
color-coded	O
for	O
ease	O
of	O
navigation	O
,	O
or	O
selected	O
elements	O
of	O
it	O
,	O
as	O
well	O
as	O
viewing	O
the	B-General_Concept
DOM	I-General_Concept
source	O
and	O
the	O
CSS	B-Language
selectors	O
that	O
are	O
applied	O
to	O
the	O
element	O
.	O
</s>
<s>
It	O
exposes	O
its	O
features	O
through	O
a	O
menu	O
hierarchy	O
and	O
includes	O
toolbar	O
buttons	O
for	O
quick	O
access	O
to	O
features	O
such	O
as	O
clearing	O
the	O
browser	O
cache	O
and	O
enabling	O
the	O
selecting	O
of	O
elements	O
by	O
clicking	O
in	O
the	O
rendered	O
page	O
,	O
rather	O
than	O
navigating	O
through	O
the	O
visual	O
representation	O
of	O
the	B-General_Concept
DOM	I-General_Concept
tree	O
.	O
</s>
