<s>
Web	B-Application
development	I-Application
tools	I-Application
(	O
often	O
called	O
devtools	B-Application
or	O
inspect	B-Application
element	I-Application
)	O
allow	O
web	B-Operating_System
developers	I-Operating_System
to	O
test	O
and	O
debug	B-Device
their	O
source	O
codes	O
.	O
</s>
<s>
They	O
are	O
different	O
from	O
website	B-Language
builders	I-Language
and	O
integrated	B-Application
development	I-Application
environments	I-Application
(	O
IDEs	O
)	O
in	O
that	O
they	O
do	O
not	O
assist	O
in	O
the	O
direct	O
creation	O
of	O
a	O
webpage	O
,	O
rather	O
they	O
are	O
tools	O
used	O
for	O
testing	O
the	O
user	B-Application
interface	I-Application
of	O
a	O
website	O
or	O
web	B-Application
application	I-Application
.	O
</s>
<s>
Web	B-Application
development	I-Application
tools	I-Application
come	O
as	O
browser	B-Application
add-ons	O
or	O
built-in	O
features	O
in	O
web	B-Application
browsers	I-Application
.	O
</s>
<s>
Most	O
popular	O
web	B-Application
browsers	I-Application
,	O
such	O
as	O
Google	B-Application
Chrome	I-Application
,	O
Firefox	B-Application
,	O
Internet	B-Application
Explorer	I-Application
,	O
Safari	B-Application
,	O
Microsoft	B-Application
Edge	I-Application
and	O
Opera	B-Application
,	O
have	O
built-in	O
tools	O
to	O
help	O
web	B-Operating_System
developers	I-Operating_System
,	O
and	O
many	O
additional	O
add-ons	O
can	O
be	O
found	O
in	O
their	O
respective	O
plugin	B-Application
download	O
centers	O
.	O
</s>
<s>
Web	B-Application
development	I-Application
tools	I-Application
allow	O
developers	O
to	O
work	O
with	O
a	O
variety	O
of	O
web	O
technologies	O
,	O
including	O
HTML	B-Language
,	O
CSS	B-Language
,	O
the	B-General_Concept
DOM	I-General_Concept
,	O
JavaScript	B-Language
,	O
and	O
other	O
components	O
that	O
are	O
handled	O
by	O
the	O
web	B-Application
browser	I-Application
.	O
</s>
<s>
Due	O
to	O
increasing	O
demand	O
from	O
web	B-Application
browsers	I-Application
to	O
do	O
more	O
,	O
popular	O
web	B-Application
browsers	I-Application
have	O
included	O
more	O
features	O
geared	O
for	O
developers	O
.	O
</s>
<s>
Several	O
notable	O
web	B-Application
browsers	I-Application
have	O
support	O
for	O
web	B-Operating_System
developer	I-Operating_System
tools	O
that	O
allow	O
web	O
designers	O
and	O
developers	O
to	O
look	O
at	O
the	O
make-up	O
of	O
their	O
pages	O
.	O
</s>
<s>
These	O
are	O
all	O
tools	O
that	O
are	O
built	O
into	O
the	O
browser	B-Application
and	O
do	O
not	O
require	O
additional	O
modules	O
or	O
configuration	O
.	O
</s>
<s>
Firefox	B-Application
–	O
opens	O
the	O
Web	B-Application
Console	I-Application
/	O
Browser	B-Application
Console	I-Application
(	O
since	O
Firefox	B-Application
4	O
)	O
.	O
</s>
<s>
The	O
Web	B-Application
Console	I-Application
applies	O
to	O
a	O
single	O
content	O
tab	O
;	O
the	O
Browser	B-Application
Console	I-Application
applies	O
to	O
the	O
whole	O
browser	B-Application
.	O
</s>
<s>
Many	O
addons	O
also	O
exist	O
,	O
including	O
Firebug	B-Operating_System
.	O
</s>
<s>
The	O
built-in	O
web	B-Operating_System
developer	I-Operating_System
tools	O
in	O
the	O
browser	B-Application
are	O
commonly	O
accessed	O
by	O
hovering	O
over	O
an	O
item	O
on	O
a	O
webpage	O
and	O
selecting	O
the	O
"	O
Inspect	B-Application
Element	I-Application
"	O
or	O
similar	O
option	O
from	O
the	O
context	O
menu	O
.	O
</s>
<s>
HTML	B-Language
and	O
DOM	B-General_Concept
viewer	O
and	O
editor	O
is	O
commonly	O
included	O
in	O
the	O
built-in	O
web	B-Application
development	I-Application
tools	I-Application
.	O
</s>
<s>
The	O
difference	O
between	O
the	O
HTML	B-Language
and	O
DOM	B-General_Concept
viewer	O
,	O
and	O
the	O
view	O
source	O
feature	O
in	O
web	B-Application
browsers	I-Application
is	O
that	O
the	O
HTML	B-Language
and	O
DOM	B-General_Concept
viewer	O
allows	O
you	O
to	O
see	O
the	B-General_Concept
DOM	I-General_Concept
as	O
it	O
was	O
rendered	O
in	O
addition	O
to	O
allowing	O
you	O
to	O
make	O
changes	O
to	O
the	O
HTML	B-Language
and	O
DOM	B-General_Concept
and	O
see	O
the	O
change	O
reflected	O
in	O
the	O
page	O
after	O
the	O
change	O
is	O
made	O
.	O
</s>
<s>
In	O
addition	O
to	O
selecting	O
and	O
editing	O
,	O
the	O
HTML	B-Language
elements	O
panels	O
will	O
usually	O
also	O
display	O
properties	O
of	O
the	B-General_Concept
DOM	I-General_Concept
object	O
,	O
such	O
as	O
display	O
dimension	O
,	O
and	O
Cascading	O
-	O
style	O
sheet	O
properties	O
.	O
</s>
<s>
Firefox	B-Application
versions	O
11	O
to	O
46	O
were	O
equipped	O
with	O
a	O
3D	O
page	O
inspector	O
using	O
WebGL	B-Library
,	O
where	O
the	O
nesting	O
of	O
elements	O
was	O
visualized	O
with	O
layers	O
protruding	O
from	O
the	O
page	O
surface	O
.	O
</s>
<s>
Web	B-Application
development	I-Application
tools	I-Application
also	O
allow	O
developers	O
to	O
inspect	O
resources	O
that	O
are	O
loaded	O
and	O
available	O
on	O
the	O
web	O
page	O
in	O
a	O
tree-structure	O
listing	O
,	O
and	O
the	O
appearance	O
of	O
style	O
sheets	O
can	O
be	O
tested	O
in	O
real	O
time	O
.	O
</s>
<s>
Web	B-Application
development	I-Application
tools	I-Application
also	O
allow	O
developers	O
to	O
view	O
information	O
about	O
the	O
network	O
usage	O
,	O
such	O
as	O
viewing	O
what	O
the	O
loading	O
time	O
and	O
bandwidth	O
usage	O
are	O
and	O
which	O
HTTP	B-Protocol
headers	I-Protocol
are	O
being	O
sent	O
and	O
received	O
.	O
</s>
<s>
Profiling	O
allows	O
developers	O
to	O
capture	O
information	O
about	O
the	O
performance	O
of	O
a	O
web	O
page	O
or	O
web	B-Application
application	I-Application
.	O
</s>
<s>
Web	B-Application
development	I-Application
tools	I-Application
typically	O
also	O
provide	O
a	O
record	O
of	O
the	O
time	O
it	O
takes	O
to	O
render	O
the	O
page	O
,	O
memory	O
usage	O
,	O
and	O
the	O
types	O
of	O
events	O
which	O
are	O
taking	O
place	O
.	O
</s>
<s>
These	O
features	O
allow	O
developers	O
to	O
optimize	O
their	O
web	O
page	O
or	O
web	B-Application
application	I-Application
.	O
</s>
<s>
JavaScript	B-Language
is	O
commonly	O
used	O
in	O
web	B-Application
browsers	I-Application
.	O
</s>
<s>
Web	B-Application
development	I-Application
tools	I-Application
commonly	O
include	O
a	O
panel	O
to	O
debug	B-Device
scripts	O
by	O
allowing	O
developers	O
to	O
add	O
watch	O
expressions	O
,	O
breakpoints	O
,	O
view	O
the	O
call	O
stack	O
,	O
and	O
pause	O
,	O
step	O
over	O
,	O
step	O
into	O
,	O
and	O
step	O
out	O
of	O
functions	O
while	O
debugging	O
JavaScript	B-Language
.	O
</s>
<s>
A	O
JavaScript	B-Language
console	O
is	O
commonly	O
included	O
.	O
</s>
<s>
The	O
consoles	O
allow	O
developers	O
to	O
type	O
in	O
JavaScript	B-Language
commands	O
and	O
call	O
functions	O
,	O
or	O
view	O
errors	O
that	O
may	O
have	O
been	O
encountered	O
during	O
the	O
execution	O
of	O
a	O
script	O
.	O
</s>
<s>
Modern	O
web	B-Application
browsers	I-Application
support	O
the	O
use	O
of	O
plugins	B-Application
or	O
extensions	O
to	O
add	O
or	O
augment	O
functionality	O
.	O
</s>
<s>
There	O
are	O
many	O
common	O
plugins	B-Application
that	O
can	O
provide	O
a	O
diverse	O
range	O
of	O
additional	O
features	O
.	O
</s>
