<s>
Dynamic	B-General_Concept
HTML	I-General_Concept
,	O
or	O
DHTML	B-General_Concept
,	O
is	O
a	O
term	O
which	O
was	O
used	O
by	O
some	O
browser	O
vendors	O
to	O
describe	O
the	O
combination	O
of	O
HTML	B-Language
,	O
style	O
sheets	O
and	O
client-side	O
scripts	O
(	O
JavaScript	B-Language
,	O
VBScript	O
,	O
or	O
any	O
other	O
supported	O
scripts	O
)	O
that	O
enabled	O
the	O
creation	O
of	O
interactive	O
and	O
animated	O
documents	O
.	O
</s>
<s>
The	O
application	O
of	O
DHTML	B-General_Concept
was	O
introduced	O
by	O
Microsoft	O
with	O
the	O
release	O
of	O
Internet	B-Protocol
Explorer	I-Protocol
4	I-Protocol
in	O
1997	O
.	O
</s>
<s>
DHTML	B-General_Concept
allows	O
scripting	O
languages	O
to	O
change	O
variables	O
in	O
a	O
web	O
page	O
's	O
definition	O
language	O
,	O
which	O
in	O
turn	O
affects	O
the	O
look	O
and	O
function	O
of	O
otherwise	O
"	O
static	O
"	O
HTML	B-Language
page	O
content	O
after	O
the	O
page	O
has	O
been	O
fully	O
loaded	O
and	O
during	O
the	O
viewing	O
process	O
.	O
</s>
<s>
Thus	O
the	O
dynamic	O
characteristic	O
of	O
DHTML	B-General_Concept
is	O
the	O
way	O
it	O
functions	O
while	O
a	O
page	O
is	O
viewed	O
,	O
not	O
in	O
its	O
ability	O
to	O
generate	O
a	O
unique	O
page	O
with	O
each	O
page	O
load	O
.	O
</s>
<s>
This	O
includes	O
pages	O
created	O
by	O
client-side	O
scripting	O
and	O
ones	O
created	O
by	O
server-side	B-Language
scripting	I-Language
(	O
such	O
as	O
PHP	B-Application
,	O
Python	B-Language
,	O
JSP	B-Language
or	O
ASP.NET	B-Application
)	O
where	O
the	O
web	O
server	O
generates	O
content	O
before	O
sending	O
it	O
to	O
the	O
client	O
.	O
</s>
<s>
DHTML	B-General_Concept
is	O
the	O
predecessor	O
of	O
Ajax	B-General_Concept
and	O
DHTML	B-General_Concept
pages	O
are	O
still	O
request/reload	O
-based	O
.	O
</s>
<s>
Under	O
the	O
DHTML	B-General_Concept
model	O
,	O
there	O
may	O
not	O
be	O
any	O
interaction	O
between	O
the	O
client	O
and	O
server	O
after	O
the	O
page	O
is	O
loaded	O
;	O
all	O
processing	O
happens	O
on	O
the	O
client	O
side	O
.	O
</s>
<s>
By	O
contrast	O
,	O
Ajax	B-General_Concept
extends	O
features	O
of	O
DHTML	B-General_Concept
to	O
allow	O
the	O
page	O
to	O
initiate	O
network	O
requests	O
(	O
or	O
'	O
subrequest	O
 '	O
)	O
to	O
the	O
server	O
even	O
after	O
page	O
load	O
to	O
perform	O
additional	O
actions	O
.	O
</s>
<s>
For	O
example	O
,	O
if	O
there	O
are	O
multiple	O
tabs	O
on	O
a	O
page	O
,	O
the	O
pure	O
DHTML	B-General_Concept
approach	O
would	O
load	O
the	O
contents	O
of	O
all	O
tabs	O
and	O
then	O
dynamically	O
display	O
only	O
the	O
one	O
that	O
is	O
active	O
,	O
while	O
AJAX	B-General_Concept
could	O
load	O
each	O
tab	O
only	O
when	O
it	O
is	O
really	O
needed	O
.	O
</s>
<s>
DHTML	B-General_Concept
allows	O
authors	O
to	O
add	O
effects	O
to	O
their	O
pages	O
that	O
are	O
otherwise	O
difficult	O
to	O
achieve	O
,	O
by	O
changing	O
the	O
Document	B-General_Concept
Object	I-General_Concept
Model	I-General_Concept
(	O
DOM	B-General_Concept
)	O
and	O
page	O
style	O
.	O
</s>
<s>
The	O
combination	O
of	O
HTML	B-Language
,	O
CSS	O
,	O
and	O
JavaScript	B-Language
offers	O
ways	O
to	O
:	O
</s>
<s>
Although	O
a	O
number	O
of	O
games	O
were	O
created	O
using	O
DHTML	B-General_Concept
during	O
the	O
late	O
1990s	O
and	O
early	O
2000s	O
,	O
differences	O
between	O
browsers	O
made	O
this	O
difficult	O
:	O
many	O
techniques	O
had	O
to	O
be	O
implemented	O
in	O
code	O
to	O
enable	O
the	O
games	O
to	O
work	O
on	O
multiple	O
platforms	O
.	O
</s>
<s>
Browsers	O
have	O
since	O
then	O
converged	O
toward	O
web	O
standards	O
,	O
which	O
has	O
made	O
the	O
design	O
of	O
DHTML	B-General_Concept
games	O
more	O
viable	O
.	O
</s>
<s>
The	O
term	O
"	O
DHTML	B-General_Concept
"	O
has	O
fallen	O
out	O
of	O
use	O
in	O
recent	O
years	O
as	O
it	O
was	O
associated	O
with	O
practices	O
and	O
conventions	O
that	O
tended	O
to	O
not	O
work	O
well	O
between	O
various	O
web	O
browsers	O
.	O
</s>
<s>
DHTML	B-General_Concept
support	O
with	O
extensive	O
DOM	B-General_Concept
access	O
was	O
introduced	O
with	O
Internet	B-Protocol
Explorer	I-Protocol
4.0	I-Protocol
.	O
</s>
<s>
Although	O
there	O
was	O
a	O
basic	O
dynamic	O
system	O
with	O
Netscape	B-Protocol
Navigator	I-Protocol
4.0	I-Protocol
,	O
not	O
all	O
HTML	B-Language
elements	O
were	O
represented	O
in	O
the	B-General_Concept
DOM	I-General_Concept
.	O
</s>
<s>
When	O
DHTML-style	O
techniques	O
became	O
widespread	O
,	O
varying	O
degrees	O
of	O
support	O
among	O
web	O
browsers	O
for	O
the	O
technologies	O
involved	O
made	O
them	O
difficult	O
to	O
develop	O
and	O
debug	B-Device
.	O
</s>
<s>
Development	O
became	O
easier	O
when	O
Internet	B-Protocol
Explorer	I-Protocol
5.0	I-Protocol
+	I-Protocol
,	O
Mozilla	B-Application
Firefox	I-Application
2.0	O
+	O
,	O
and	O
Opera	B-Application
7.0	O
+	O
adopted	O
a	O
shared	O
DOM	B-General_Concept
inherited	O
from	O
ECMAScript	B-Language
.	O
</s>
<s>
Later	O
,	O
JavaScript	B-Language
libraries	I-Language
such	O
as	O
jQuery	B-Language
abstracted	O
away	O
many	O
of	O
the	O
day-to-day	O
difficulties	O
in	O
cross-browser	O
DOM	B-General_Concept
manipulation	O
,	O
though	O
better	O
standards	O
compliance	O
among	O
browsers	O
has	O
reduced	O
the	O
need	O
for	O
this	O
.	O
</s>
<s>
Typically	O
a	O
web	O
page	O
using	O
DHTML	B-General_Concept
is	O
set	O
up	O
in	O
the	O
following	O
way	O
:	O
</s>
<s>
DHTML	B-General_Concept
is	O
not	O
a	O
technology	O
in	O
and	O
of	O
itself	O
;	O
rather	O
,	O
it	O
is	O
the	O
product	O
of	O
three	O
related	O
and	O
complementary	O
technologies	O
:	O
HTML	B-Language
,	O
Cascading	O
Style	O
Sheets	O
(	O
CSS	O
)	O
,	O
and	O
JavaScript	B-Language
.	O
</s>
<s>
To	O
allow	O
scripts	O
and	O
components	O
to	O
access	O
features	O
of	O
HTML	B-Language
and	O
CSS	O
,	O
the	O
contents	O
of	O
the	O
document	O
are	O
represented	O
as	O
objects	O
in	O
a	O
programming	O
model	O
known	O
as	O
the	O
Document	B-General_Concept
Object	I-General_Concept
Model	I-General_Concept
(	O
DOM	B-General_Concept
)	O
.	O
</s>
<s>
The	B-General_Concept
DOM	I-General_Concept
API	O
is	O
the	O
foundation	O
of	O
DHTML	B-General_Concept
,	O
providing	O
a	O
structured	O
interface	O
that	O
allows	O
access	O
and	O
manipulation	O
of	O
virtually	O
anything	O
in	O
the	O
document	O
.	O
</s>
<s>
The	O
HTML	B-Language
elements	O
in	O
the	O
document	O
are	O
available	O
as	O
a	O
hierarchical	O
tree	B-Application
of	O
individual	O
objects	O
,	O
making	O
it	O
possible	O
to	O
examine	O
and	O
modify	O
an	O
element	O
and	O
its	O
attributes	O
by	O
reading	O
and	O
setting	O
properties	O
and	O
by	O
calling	O
methods	O
.	O
</s>
<s>
The	O
text	O
between	O
elements	O
is	O
also	O
available	O
through	O
DOM	B-General_Concept
properties	O
and	O
methods	O
.	O
</s>
<s>
The	B-General_Concept
DOM	I-General_Concept
also	O
provides	O
access	O
to	O
user	O
actions	O
such	O
as	O
pressing	O
a	O
key	O
and	O
clicking	O
the	O
mouse	O
.	O
</s>
<s>
The	O
event	O
handler	O
receives	O
control	O
each	O
time	O
a	O
given	O
event	O
occurs	O
and	O
can	O
carry	O
out	O
any	O
appropriate	O
action	O
,	O
including	O
using	O
the	B-General_Concept
DOM	I-General_Concept
to	O
change	O
the	O
document	O
.	O
</s>
<s>
Dynamic	O
styles	O
are	O
a	O
key	O
feature	O
of	O
DHTML	B-General_Concept
.	O
</s>
<s>
This	O
means	O
you	O
can	O
change	O
inline	O
styles	O
on	O
individual	O
elements	O
and	O
change	O
style	O
rules	O
using	O
simple	O
JavaScript	B-Language
programming	O
.	O
</s>
