<s>
A	O
node	O
is	O
a	O
basic	O
unit	O
of	O
a	O
data	B-General_Concept
structure	I-General_Concept
,	O
such	O
as	O
a	O
linked	B-Data_Structure
list	I-Data_Structure
or	O
tree	B-Application
data	I-Application
structure	I-Application
.	O
</s>
<s>
Nodes	O
are	O
often	O
arranged	O
into	O
tree	B-Application
structures	O
.	O
</s>
<s>
A	O
node	O
represents	O
the	O
information	O
contained	O
in	O
a	O
single	O
data	B-General_Concept
structure	I-General_Concept
.	O
</s>
<s>
These	O
nodes	O
may	O
contain	O
a	O
value	O
or	O
condition	O
,	O
or	O
possibly	O
serve	O
as	O
another	O
independent	O
data	B-General_Concept
structure	I-General_Concept
.	O
</s>
<s>
Nodes	O
are	O
represented	O
by	O
a	O
single	O
parent	B-Application
node	I-Application
.	O
</s>
<s>
The	O
highest	O
point	O
on	O
a	O
tree	B-Application
structure	O
is	O
called	O
a	O
root	B-Application
node	I-Application
,	O
which	O
does	O
not	O
have	O
a	O
parent	B-Application
node	I-Application
,	O
but	O
serves	O
as	O
the	O
parent	O
or	O
'	O
grandparent	O
 '	O
of	O
all	O
of	O
the	O
nodes	O
below	O
it	O
in	O
the	O
tree	B-Application
.	O
</s>
<s>
The	O
height	O
of	O
a	O
node	O
is	O
determined	O
by	O
the	O
total	O
number	O
of	O
edges	O
on	O
the	O
path	O
from	O
that	O
node	O
to	O
the	O
furthest	O
leaf	O
node	O
,	O
and	O
the	O
height	O
of	O
the	O
tree	B-Application
is	O
equal	O
to	O
the	O
height	O
of	O
the	O
root	B-Application
node	I-Application
.	O
</s>
<s>
Node	O
depth	O
is	O
determined	O
by	O
the	O
distance	O
between	O
that	O
particular	O
node	O
and	O
the	O
root	B-Application
node	I-Application
.	O
</s>
<s>
The	O
root	B-Application
node	I-Application
is	O
said	O
to	O
have	O
a	O
depth	O
of	O
zero	O
.	O
</s>
<s>
The	O
inverse	O
relationship	O
is	O
that	O
of	O
a	O
parent	B-Application
node	I-Application
.	O
</s>
<s>
If	O
node	O
C	O
is	O
a	O
child	O
of	O
node	O
A	O
,	O
then	O
A	O
is	O
the	O
parent	B-Application
node	I-Application
of	O
C	O
.	O
</s>
<s>
Depth	O
:	O
the	O
depth	O
of	O
node	O
A	O
is	O
the	O
length	O
of	O
the	O
path	O
from	O
A	O
to	O
the	O
root	B-Application
node	I-Application
.	O
</s>
<s>
The	O
root	B-Application
node	I-Application
is	O
said	O
to	O
have	O
depth	O
0	O
.	O
</s>
<s>
Root	B-Application
node	I-Application
:	O
a	O
node	O
distinguished	O
from	O
the	O
rest	O
of	O
the	O
tree	B-Application
nodes	O
.	O
</s>
<s>
Usually	O
,	O
it	O
is	O
depicted	O
as	O
the	O
highest	O
node	O
of	O
the	O
tree	B-Application
.	O
</s>
<s>
Sibling	O
nodes	O
:	O
these	O
are	O
nodes	O
connected	O
to	O
the	O
same	O
parent	B-Application
node	I-Application
.	O
</s>
<s>
In	O
programming	O
,	O
XML	B-Protocol
is	O
used	O
to	O
communicate	O
information	O
between	O
computer	O
programmers	O
and	O
computers	O
alike	O
.	O
</s>
<s>
For	O
this	O
reason	O
XML	B-Protocol
is	O
used	O
to	O
create	O
common	O
communication	O
protocols	O
used	O
in	O
office	O
productivity	O
software	O
,	O
and	O
serves	O
as	O
the	O
base	O
for	O
the	O
development	O
of	O
modern	O
web	O
markup	O
languages	O
like	O
XHTML	B-Language
.	O
</s>
<s>
Though	O
similar	O
in	O
how	O
it	O
is	O
approached	O
by	O
a	O
programmer	O
,	O
HTML	B-Language
and	O
CSS	B-Language
is	O
typically	O
the	O
language	O
used	O
to	O
develop	O
website	O
text	O
and	O
design	O
.	O
</s>
<s>
While	O
XML	B-Protocol
,	O
HTML	B-Language
and	O
XHTML	B-Language
provide	O
the	O
language	O
and	O
expression	O
,	O
the	B-General_Concept
DOM	I-General_Concept
serves	O
as	O
a	O
translator	O
.	O
</s>
<s>
Different	O
types	O
of	O
nodes	O
in	O
a	O
tree	B-Application
are	O
represented	O
by	O
specific	O
interfaces	O
.	O
</s>
<s>
A	O
node	O
object	O
is	O
represented	O
by	O
a	O
single	O
node	O
in	O
a	O
tree	B-Application
.	O
</s>
<s>
For	O
example	O
,	O
with	O
text	O
nodes	O
that	O
cannot	O
have	O
child	O
nodes	O
,	O
trying	O
to	O
add	O
child	O
nodes	O
results	O
in	O
a	O
DOM	B-General_Concept
error	O
.	O
</s>
<s>
Objects	O
in	O
the	B-General_Concept
DOM	I-General_Concept
tree	B-Application
may	O
be	O
addressed	O
and	O
manipulated	O
by	O
using	O
methods	O
on	O
the	O
objects	O
.	O
</s>
<s>
The	O
public	O
interface	O
of	O
a	O
DOM	B-General_Concept
is	O
specified	O
in	O
its	O
application	B-Application
programming	I-Application
interface	I-Application
(	O
API	B-Application
)	O
.	O
</s>
<s>
The	O
history	O
of	O
the	O
Document	B-General_Concept
Object	I-General_Concept
Model	I-General_Concept
is	O
intertwined	O
with	O
the	O
history	O
of	O
the	O
"	O
browser	B-Application
wars	I-Application
"	O
of	O
the	O
late	O
1990s	O
between	O
Netscape	B-Protocol
Navigator	I-Protocol
and	O
Microsoft	B-Application
Internet	I-Application
Explorer	I-Application
,	O
as	O
well	O
as	O
with	O
that	O
of	O
JavaScript	B-Language
and	O
JScript	B-Language
,	O
the	O
first	O
scripting	B-Language
languages	I-Language
to	O
be	O
widely	O
implemented	O
in	O
the	O
layout	B-Protocol
engines	I-Protocol
of	O
web	B-Application
browsers	I-Application
.	O
</s>
