<s>
An	O
HTML	B-Language
element	O
is	O
a	O
type	O
of	O
HTML	B-Language
(	O
HyperText	B-Language
Markup	I-Language
Language	I-Language
)	O
document	O
component	O
,	O
one	O
of	O
several	O
types	O
of	O
HTML	B-Language
nodes	B-Data_Structure
(	O
there	O
are	O
also	O
text	O
nodes	B-Data_Structure
,	O
comment	O
nodes	B-Data_Structure
and	O
others	O
)	O
.	O
</s>
<s>
The	O
first	O
used	O
version	O
of	O
HTML	B-Language
was	O
written	O
by	O
Tim	O
Berners-Lee	O
in	O
1993	O
and	O
there	O
have	O
since	O
been	O
many	O
versions	O
of	O
HTML	B-Language
.	O
</s>
<s>
The	O
most	O
commonly	O
used	O
version	O
is	O
HTML	B-Language
4.01	I-Language
,	O
which	O
became	O
official	O
standard	O
in	O
December	O
1999	O
.	O
</s>
<s>
An	O
HTML	B-Language
document	O
is	O
composed	O
of	O
a	O
tree	B-Data_Structure
of	O
simple	O
HTML	B-Language
nodes	B-Data_Structure
,	O
such	O
as	O
text	O
nodes	B-Data_Structure
,	O
and	O
HTML	B-Language
elements	O
,	O
which	O
add	O
semantics	B-Application
and	O
formatting	O
to	O
parts	O
of	O
document	O
(	O
e.g.	O
,	O
make	O
text	O
bold	O
,	O
organize	O
it	O
into	O
paragraphs	O
,	O
lists	O
and	O
tables	O
,	O
or	O
embed	O
hyperlinks	O
and	O
images	O
)	O
.	O
</s>
<s>
Each	O
element	O
can	O
have	O
HTML	B-General_Concept
attributes	I-General_Concept
specified	O
.	O
</s>
<s>
This	O
is	O
the	O
case	O
for	O
many	O
,	O
but	O
not	O
all	O
,	O
elements	O
within	O
an	O
HTML	B-Language
document	O
.	O
</s>
<s>
The	O
distinction	O
is	O
explicitly	O
emphasised	O
in	O
HTML	B-Language
4.01	I-Language
Specification	O
:	O
</s>
<s>
Similarly	O
the	O
W3C	O
Recommendation	O
HTML	B-Application
5.1	I-Application
2nd	O
Edition	O
explicitly	O
says	O
:	O
</s>
<s>
As	O
HTML	B-Language
(	O
before	O
HTML5	B-Application
)	O
is	O
based	O
on	O
SGML	B-Language
,	O
its	O
parsing	O
also	O
depends	O
on	O
the	O
Document	B-Language
Type	I-Language
Definition	I-Language
(	O
DTD	B-Language
)	O
,	O
specifically	O
an	O
HTML	B-Language
DTD	B-Language
(	O
e.g.	O
</s>
<s>
HTML	B-Language
4.01	I-Language
)	O
.	O
</s>
<s>
The	O
DTD	B-Language
specifies	O
which	O
element	O
types	O
are	O
possible	O
(	O
i.e.	O
</s>
<s>
it	O
defines	O
the	O
set	O
of	O
element	O
types	O
)	O
and	O
also	O
the	O
valid	B-Application
combinations	O
in	O
which	O
they	O
may	O
appear	O
in	O
a	O
document	O
.	O
</s>
<s>
It	O
is	O
part	O
of	O
general	O
SGML	B-Language
behavior	O
that	O
,	O
where	O
only	O
one	O
valid	B-Application
structure	O
is	O
(	O
per	O
the	O
DTD	B-Language
)	O
,	O
its	O
explicit	O
statement	O
in	O
any	O
given	O
document	O
is	O
not	O
generally	O
required	O
.	O
</s>
<s>
But	O
since	O
the	O
DTD	B-Language
states	O
that	O
paragraph	O
elements	O
cannot	O
be	O
nested	O
,	O
an	O
HTML	B-Language
document	O
fragment	O
is	O
thus	O
inferred	O
to	O
be	O
equivalent	O
to	O
.	O
</s>
<s>
Because	O
this	O
implication	O
is	O
based	O
on	O
the	O
combination	O
of	O
the	O
DTD	B-Language
and	O
the	O
individual	O
document	O
,	O
it	O
is	O
not	O
usually	O
possible	O
to	O
infer	O
elements	O
from	O
document	O
tags	O
but	O
only	O
by	O
using	O
an	O
SGML	B-Language
—	O
or	O
HTML	B-Language
—	O
aware	O
parser	O
with	O
knowledge	O
of	O
the	O
DTD	B-Language
.	O
</s>
<s>
HTML5	B-Application
creates	O
a	O
similar	O
result	O
by	O
defining	O
what	O
tags	O
can	O
be	O
omitted	O
.	O
</s>
<s>
SGML	B-Language
is	O
complex	O
,	O
which	O
has	O
limited	O
its	O
widespread	O
understanding	O
and	O
adoption	O
.	O
</s>
<s>
XML	B-Protocol
was	O
developed	O
as	O
a	O
simpler	O
alternative	O
.	O
</s>
<s>
Although	O
both	O
can	O
use	O
the	O
DTD	B-Language
to	O
specify	O
the	O
supported	O
elements	O
and	O
their	O
permitted	O
combinations	O
as	O
document	O
structure	O
,	O
XML	B-Protocol
parsing	O
is	O
simpler	O
.	O
</s>
<s>
The	O
relation	O
from	O
tags	O
to	O
elements	O
is	O
always	O
that	O
of	O
parsing	O
the	O
actual	O
tags	O
included	O
in	O
the	O
document	O
,	O
without	O
the	O
implied	O
closures	O
that	O
are	O
part	O
of	O
SGML	B-Language
.	O
</s>
<s>
HTML	B-Language
as	O
used	O
on	O
the	O
current	O
web	O
is	O
likely	O
to	O
be	O
either	O
treated	O
as	O
XML	B-Protocol
,	O
by	O
being	O
XHTML	B-Language
,	O
or	O
as	O
HTML5	B-Application
;	O
in	O
either	O
case	O
the	O
parsing	O
of	O
document	O
tags	O
into	O
Document	B-General_Concept
Object	I-General_Concept
Model	I-General_Concept
(	O
DOM	B-General_Concept
)	O
elements	O
is	O
simplified	O
compared	O
to	O
legacy	O
HTML	B-Language
systems	O
.	O
</s>
<s>
Once	O
the	B-General_Concept
DOM	I-General_Concept
of	O
elements	O
is	O
obtained	O
,	O
behavior	O
at	O
higher	O
levels	O
of	O
interface	O
(	O
example	O
:	O
screen	O
rendering	O
)	O
is	O
identical	O
or	O
nearly	O
so	O
.	O
</s>
<s>
Part	O
of	O
this	O
CSS	B-Language
presentation	O
behavior	O
is	O
the	O
notion	O
of	O
the	O
"	O
box	O
model	O
"	O
.	O
</s>
<s>
This	O
is	O
applied	O
to	O
those	O
elements	O
that	O
CSS	B-Language
considers	O
to	O
be	O
"	O
block	O
"	O
elements	O
,	O
set	O
through	O
the	O
CSS	B-Language
declaration	O
.	O
</s>
<s>
HTML	B-Language
also	O
has	O
a	O
similar	O
concept	O
,	O
although	O
different	O
,	O
and	O
the	O
two	O
are	O
very	O
frequently	O
confused	O
.	O
</s>
<s>
%block	O
;	O
and	O
%inline	O
;	O
are	O
groups	O
within	O
the	O
HTML	B-Language
DTD	B-Language
that	O
group	O
elements	O
as	O
being	O
either	O
"	O
block-level	O
"	O
or	O
"	O
inline	O
"	O
.	O
</s>
<s>
This	O
behavior	O
cannot	O
be	O
changed	O
;	O
it	O
is	O
fixed	O
in	O
the	O
DTD	B-Language
.	O
</s>
<s>
Block	O
and	O
inline	O
elements	O
have	O
the	O
appropriate	O
and	O
different	O
CSS	B-Language
behaviors	O
attached	O
to	O
them	O
by	O
default	O
,	O
including	O
the	O
relevance	O
of	O
the	O
box	O
model	O
for	O
particular	O
element	O
types	O
.	O
</s>
<s>
Note	O
though	O
that	O
this	O
CSS	B-Language
behavior	O
can	O
,	O
and	O
frequently	O
is	O
,	O
changed	O
from	O
the	O
default	O
.	O
</s>
<s>
Lists	O
with	O
{{	O
code|lang	O
=	O
html|code	O
=	O
<ul>	O
...	O
}}	O
are	O
%block	O
;	O
elements	O
and	O
are	O
presented	O
as	O
block	O
elements	O
by	O
default	O
.	O
</s>
<s>
However	O
,	O
it	O
is	O
quite	O
common	O
to	O
set	O
these	O
with	O
CSS	B-Language
to	O
display	O
as	O
an	O
inline	O
list	O
.	O
</s>
<s>
In	O
the	O
HTML	B-Language
syntax	I-Language
,	O
most	O
elements	O
are	O
written	O
with	O
a	O
start	O
tag	O
and	O
an	O
end	O
tag	O
,	O
with	O
the	O
content	O
in	O
between	O
.	O
</s>
<s>
An	O
HTML	B-Language
tag	O
is	O
composed	O
of	O
the	O
name	O
of	O
the	O
element	O
,	O
surrounded	O
by	O
angle	O
brackets	O
.	O
</s>
<s>
When	O
using	O
XHTML	B-Language
,	O
it	O
is	O
required	O
to	O
open	O
and	O
close	O
all	O
elements	O
,	O
including	O
void	O
elements	O
.	O
</s>
<s>
This	O
can	O
be	O
done	O
by	O
placing	O
an	O
end	O
tag	O
immediately	O
after	O
the	O
start	O
tag	O
,	O
but	O
this	O
is	O
not	O
legal	O
in	O
HTML	B-Application
5	I-Application
and	O
will	O
lead	O
to	O
two	O
elements	O
being	O
created	O
.	O
</s>
<s>
An	O
alternative	O
way	O
to	O
specify	O
that	O
it	O
is	O
a	O
void	O
element	O
,	O
which	O
is	O
compatible	O
with	O
both	O
XHTML	B-Language
and	O
HTML	B-Application
5	I-Application
,	O
is	O
to	O
put	O
a	O
/	O
at	O
the	O
of	O
the	O
tag	O
(	O
not	O
to	O
be	O
confused	O
with	O
the	O
/	O
at	O
the	O
of	O
a	O
closing	O
tag	O
)	O
.	O
</s>
<s>
HTML	B-General_Concept
attributes	I-General_Concept
are	O
specified	O
inside	O
the	O
start	O
tag	O
.	O
</s>
<s>
Informally	O
,	O
HTML	B-Language
elements	O
are	O
sometimes	O
referred	O
to	O
as	O
"	O
tags	O
"	O
(	O
an	O
example	O
of	O
synecdoche	O
)	O
,	O
though	O
many	O
prefer	O
the	O
term	O
tag	O
strictly	O
in	O
reference	O
to	O
the	O
markup	O
delimiting	O
the	O
start	O
and	O
end	O
of	O
an	O
element	O
.	O
</s>
<s>
Element	O
(	O
and	O
attribute	O
)	O
names	O
may	O
be	O
written	O
in	O
any	O
combination	O
of	O
upper	O
or	O
lower	O
case	O
in	O
HTML	B-Language
,	O
but	O
must	O
be	O
in	O
lower	O
case	O
in	O
XHTML	B-Language
.	O
</s>
<s>
The	O
canonical	O
form	B-General_Concept
was	O
upper-case	O
until	O
HTML	B-Language
4	O
,	O
and	O
was	O
used	O
in	O
HTML	B-Language
specifications	O
,	O
but	O
in	O
recent	O
years	O
,	O
lower-case	O
has	O
become	O
more	O
common	O
.	O
</s>
<s>
There	O
are	O
three	O
kinds	O
of	O
HTML	B-Language
elements	O
:	O
normal	O
elements	O
,	O
raw	O
text	O
elements	O
,	O
and	O
void	O
elements	O
.	O
</s>
<s>
a	O
start	O
tag	O
(	O
)	O
marking	O
the	O
beginning	O
of	O
an	O
element	O
,	O
which	O
may	O
incorporate	O
any	O
number	O
of	O
HTML	B-General_Concept
attributes	I-General_Concept
;	O
</s>
<s>
a	O
start	O
tag	O
(	O
in	O
the	O
form	B-General_Concept
)	O
marking	O
the	O
beginning	O
of	O
an	O
element	O
,	O
which	O
may	O
incorporate	O
any	O
number	O
of	O
HTML	B-General_Concept
attributes	I-General_Concept
;	O
</s>
<s>
In	O
some	O
versions	O
of	O
HTML	B-Language
,	O
the	O
end	O
tag	O
is	O
optional	O
for	O
some	O
elements	O
.	O
</s>
<s>
The	O
end	O
tag	O
is	O
required	O
in	O
XHTML	B-Language
.	O
</s>
<s>
(	O
also	O
sometimes	O
called	O
empty	O
elements	O
,	O
single	O
elements	O
or	O
stand-alone	O
elements	O
)	O
only	O
have	O
a	O
start	O
tag	O
(	O
in	O
the	O
form	B-General_Concept
)	O
,	O
which	O
contains	O
any	O
HTML	B-General_Concept
attributes	I-General_Concept
.	O
</s>
<s>
For	O
compatibility	O
with	O
XHTML	B-Language
,	O
the	O
HTML	B-Language
specification	O
allows	O
an	O
optional	O
space	O
and	O
slash	O
(	O
is	O
permissible	O
)	O
.	O
</s>
<s>
The	O
slash	O
is	O
required	O
in	O
XHTML	B-Language
and	O
other	O
XML	B-Protocol
applications	O
.	O
</s>
<s>
This	O
element	O
points	O
the	O
browser	B-Application
at	O
a	O
style	O
sheet	O
to	O
use	O
when	O
presenting	O
the	O
HTML	B-Language
document	O
to	O
the	O
user	O
.	O
</s>
<s>
Note	O
that	O
in	O
the	O
HTML	B-Language
syntax	I-Language
attributes	O
do	O
n't	O
have	O
to	O
be	O
quoted	O
if	O
they	O
are	O
composed	O
only	O
of	O
certain	O
characters	O
:	O
letters	O
,	O
digits	O
,	O
the	O
hyphen-minus	O
and	O
the	O
period	O
.	O
</s>
<s>
When	O
using	O
the	O
XML	B-Protocol
syntax	O
(	O
XHTML	B-Language
)	O
,	O
on	O
the	O
other	O
hand	O
,	O
all	O
attributes	O
must	O
be	O
quoted	O
,	O
and	O
a	O
spaced	O
trailing	O
slash	O
is	O
required	O
before	O
the	O
last	O
angle	O
bracket	O
:	O
</s>
<s>
HTML	B-General_Concept
attributes	I-General_Concept
define	O
desired	O
behavior	O
or	O
indicate	O
additional	O
element	O
properties	O
.	O
</s>
<s>
In	O
HTML	B-Language
,	O
the	O
value	O
can	O
be	O
left	O
unquoted	O
if	O
it	O
does	O
not	O
include	O
spaces	O
(=	O
)	O
,	O
or	O
it	O
can	O
be	O
quoted	O
with	O
single	O
or	O
double	O
quotes	O
(=	O
''	O
or	O
=""	O
)	O
.	O
</s>
<s>
In	O
XML	B-Protocol
,	O
those	O
quotes	O
are	O
required	O
.	O
</s>
<s>
In	O
the	O
XML	B-Protocol
(	O
and	O
thus	O
XHTML	B-Language
)	O
syntax	O
,	O
though	O
,	O
a	O
value	O
is	O
required	O
,	O
and	O
the	O
name	O
should	O
be	O
repeated	O
as	O
the	O
value	O
:	O
</s>
<s>
HTML	B-Language
elements	O
are	O
defined	O
in	O
a	O
series	O
of	O
freely	O
available	O
open	O
standards	O
issued	O
since	O
1995	O
,	O
initially	O
by	O
the	O
IETF	O
and	O
subsequently	O
by	O
the	O
W3C	O
.	O
</s>
<s>
During	O
the	O
browser	B-Application
wars	I-Application
of	O
the	O
1990s	O
,	O
developers	O
of	O
user	B-Protocol
agents	I-Protocol
(	O
e.g.	O
</s>
<s>
web	B-Application
browsers	I-Application
)	O
often	O
developed	O
their	O
own	O
elements	O
,	O
some	O
of	O
which	O
have	O
been	O
adopted	O
in	O
later	O
standards	O
.	O
</s>
<s>
Other	O
user	B-Protocol
agents	I-Protocol
may	O
not	O
recognize	O
non-standard	O
elements	O
,	O
and	O
they	O
will	O
be	O
ignored	O
,	O
possibly	O
causing	O
the	O
page	O
to	O
be	O
displayed	O
improperly	O
.	O
</s>
<s>
In	O
1998	O
,	O
XML	B-Protocol
(	O
a	O
simplified	O
form	B-General_Concept
of	O
SGML	B-Language
)	O
introduced	O
mechanisms	O
to	O
allow	O
anyone	O
to	O
develop	O
their	O
own	O
elements	O
and	O
incorporate	O
them	O
in	O
XHTML	B-Language
documents	O
,	O
for	O
use	O
with	O
XML-aware	O
user	B-Protocol
agents	I-Protocol
.	O
</s>
<s>
Subsequently	O
,	O
HTML	B-Language
4.01	I-Language
was	O
rewritten	O
in	O
an	O
XML-compatible	O
form	B-General_Concept
,	O
XHTML	B-Language
1.0	I-Language
(	O
eXtensible	O
HTML	B-Language
)	O
.	O
</s>
<s>
The	O
elements	O
in	O
each	O
are	O
identical	O
,	O
and	O
in	O
most	O
cases	O
valid	B-Application
XHTML	B-Language
1.0	I-Language
documents	O
will	O
be	O
valid	B-Application
or	O
nearly	O
valid	B-Application
HTML	B-Language
4.01	I-Language
documents	O
.	O
</s>
<s>
This	O
article	O
mainly	O
focuses	O
on	O
real	O
HTML	B-Language
,	O
unless	O
noted	O
otherwise	O
;	O
however	O
,	O
it	O
remains	O
applicable	O
to	O
XHTML	B-Language
.	O
</s>
<s>
See	O
HTML	B-Language
for	O
a	O
discussion	O
of	O
the	O
minor	O
differences	O
between	O
the	O
two	O
.	O
</s>
<s>
Since	O
the	O
first	O
version	O
of	O
HTML	B-Language
,	O
several	O
elements	O
have	O
become	O
outmoded	O
,	O
and	O
are	O
deprecated	B-General_Concept
in	O
later	O
standards	O
,	O
or	O
do	O
not	O
appear	O
at	O
all	O
,	O
in	O
which	O
case	O
they	O
are	O
invalid	O
(	O
and	O
will	O
be	O
found	O
invalid	O
,	O
and	O
perhaps	O
not	O
displayed	O
,	O
by	O
validating	B-Language
user	B-Protocol
agents	I-Protocol
)	O
.	O
</s>
<s>
In	O
HTML	B-Language
4.01	I-Language
/	O
XHTML	B-Language
1.0	I-Language
,	O
the	O
status	O
of	O
elements	O
is	O
complicated	O
by	O
the	O
existence	O
of	O
three	O
types	O
of	O
DTD	B-Language
:	O
</s>
<s>
Transitional	O
,	O
which	O
contain	O
deprecated	B-General_Concept
elements	O
,	O
but	O
which	O
were	O
intended	O
to	O
provide	O
a	O
transitional	O
period	O
during	O
which	O
authors	O
could	O
update	O
their	O
practices	O
;	O
</s>
<s>
Frameset	O
,	O
which	O
are	O
versions	O
of	O
the	O
Transitional	O
DTDs	B-Language
which	O
also	O
allow	O
authors	O
to	O
write	O
frameset	O
documents	O
;	O
</s>
<s>
Strict	O
,	O
which	O
is	O
the	O
up-to-date	O
(	O
as	O
at	O
1999	O
)	O
form	B-General_Concept
of	O
HTML	B-Language
.	O
</s>
<s>
HTML5	B-Application
instead	O
provides	O
a	O
listing	O
of	O
obsolete	O
features	O
to	O
go	O
along	O
with	O
the	O
standardized	O
normative	O
content	O
.	O
</s>
<s>
The	O
first	O
Standard	O
(	O
HTML	B-Language
2.0	O
)	O
contained	O
four	O
deprecated	B-General_Concept
elements	O
,	O
one	O
of	O
which	O
was	O
invalid	O
in	O
HTML	B-Language
3.2	O
.	O
</s>
<s>
All	O
four	O
are	O
invalid	O
in	O
HTML	B-Language
4.01	I-Language
Transitional	O
,	O
which	O
also	O
deprecated	B-General_Concept
a	O
further	O
ten	O
elements	O
.	O
</s>
<s>
All	O
of	O
these	O
,	O
plus	O
two	O
others	O
,	O
are	O
invalid	O
in	O
HTML	B-Language
4.01	I-Language
Strict	O
.	O
</s>
<s>
While	O
the	O
frame	O
elements	O
are	O
still	O
current	O
in	O
the	O
sense	O
of	O
being	O
present	O
in	O
the	O
Transitional	O
and	O
Frameset	O
DTDs	B-Language
,	O
there	O
are	O
no	O
plans	O
to	O
preserve	O
them	O
in	O
future	O
standards	O
,	O
as	O
their	O
function	O
has	O
been	O
largely	O
replaced	O
,	O
and	O
they	O
are	O
highly	O
problematic	O
for	O
user	O
accessibility	O
.	O
</s>
<s>
(	O
Strictly	O
speaking	O
,	O
the	O
most	O
recent	O
XHTML	B-Language
standard	O
,	O
XHTML	B-Language
1.1	O
(	O
2001	O
)	O
,	O
does	O
not	O
include	O
frames	O
at	O
all	O
;	O
it	O
is	O
approximately	O
equivalent	O
to	O
XHTML	B-Language
1.0	I-Language
Strict	I-Language
,	O
but	O
also	O
includes	O
the	O
Ruby	O
markup	O
module	O
.	O
)	O
</s>
<s>
A	O
common	O
source	O
of	O
confusion	O
is	O
the	O
loose	O
use	O
of	O
deprecated	B-General_Concept
to	O
refer	O
to	O
both	O
deprecated	B-General_Concept
and	O
invalid	O
status	O
,	O
and	O
to	O
elements	O
that	O
are	O
expected	O
to	O
be	O
formally	O
deprecated	B-General_Concept
in	O
the	O
future	O
.	O
</s>
<s>
Since	O
HTML	B-Language
4	O
,	O
HTML	B-Language
has	O
increasingly	O
focused	O
on	O
the	O
separation	O
of	O
content	O
(	O
the	O
visible	O
text	O
and	O
images	O
)	O
from	O
presentation	O
(	O
like	O
color	O
,	O
font	O
size	O
,	O
and	O
layout	O
)	O
.	O
</s>
<s>
HTML	B-Language
is	O
used	O
to	O
represent	O
the	O
structure	O
or	O
content	O
of	O
a	O
document	O
,	O
its	O
presentation	O
remains	O
the	O
sole	O
responsibility	O
of	O
CSS	B-Language
style	I-Language
sheets	I-Language
.	O
</s>
<s>
A	O
default	O
style	O
sheet	O
is	O
suggested	O
as	O
part	O
of	O
the	O
CSS	B-Language
standard	O
,	O
giving	O
a	O
default	O
rendering	O
for	O
HTML	B-Language
.	O
</s>
<s>
Separation	O
of	O
concerns	O
allows	O
the	O
document	O
to	O
be	O
presented	O
by	O
different	O
user	B-Protocol
agents	I-Protocol
according	O
to	O
their	O
purposes	O
and	O
abilities	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
user	B-Protocol
agent	I-Protocol
can	O
select	O
an	O
appropriate	O
style	O
sheet	O
to	O
present	O
a	O
document	O
by	O
displaying	O
on	O
a	O
monitor	O
,	O
printing	O
on	O
paper	O
,	O
or	O
to	O
determine	O
speech	O
characteristics	O
in	O
an	O
audio-only	O
user	B-Protocol
agent	I-Protocol
.	O
</s>
<s>
Historically	O
,	O
user	B-Protocol
agents	I-Protocol
did	O
not	O
always	O
support	O
these	O
features	O
.	O
</s>
<s>
In	O
the	O
1990s	O
,	O
as	O
a	O
stop-gap	O
,	O
presentational	O
elements	O
(	O
like	O
and	O
)	O
were	O
added	O
to	O
HTML	B-Language
,	O
at	O
the	O
cost	O
of	O
creating	O
problems	O
for	O
interoperability	O
and	O
user	O
accessibility	O
.	O
</s>
<s>
This	O
is	O
now	O
regarded	O
as	O
outmoded	O
and	O
has	O
been	O
superseded	O
by	O
style	O
sheet-based	O
design	O
;	O
most	O
presentational	O
elements	O
are	O
now	O
deprecated	B-General_Concept
.	O
</s>
<s>
(	O
With	O
XHTML	B-Language
,	O
the	O
SVG	B-Application
language	O
can	O
also	O
be	O
used	O
to	O
write	O
graphics	O
within	O
the	O
document	O
,	O
though	O
linking	O
to	O
external	O
SVG	B-Application
files	I-Application
is	O
generally	O
simpler	O
.	O
)	O
</s>
<s>
Where	O
an	O
image	O
is	O
not	O
purely	O
decorative	O
,	O
HTML	B-Language
allows	O
replacement	O
content	O
with	O
similar	O
semantic	O
value	O
to	O
be	O
provided	O
for	O
non-visual	O
user	B-Protocol
agents	I-Protocol
.	O
</s>
<s>
An	O
HTML	B-Language
document	O
can	O
also	O
be	O
extended	O
through	O
the	O
use	O
of	O
scripts	O
to	O
provide	O
additional	O
behaviors	O
beyond	O
the	O
abilities	O
of	O
HTML	B-Language
hyperlinks	O
and	O
forms	O
.	O
</s>
<s>
The	O
elements	O
and	O
,	O
with	O
related	O
HTML	B-General_Concept
attributes	I-General_Concept
,	O
provide	O
style	B-Language
sheets	I-Language
and	O
scripts	O
.	O
</s>
<s>
(	O
The	O
element	O
can	O
also	O
be	O
used	O
to	O
link	O
style	B-Language
sheets	I-Language
.	O
)	O
</s>
<s>
For	O
user	B-Protocol
agents	I-Protocol
which	O
do	O
not	O
operate	O
scripts	O
,	O
the	O
element	O
provides	O
embedded	O
alternative	O
content	O
where	O
appropriate	O
;	O
however	O
,	O
it	O
can	O
only	O
be	O
used	O
in	O
the	O
document	O
head	O
and	O
in	O
the	O
body	O
as	O
a	O
block-level	O
element	O
.	O
</s>
<s>
In	O
visual	O
browsers	B-Application
,	O
displayable	O
elements	O
can	O
be	O
rendered	O
as	O
either	O
block	O
or	O
inline	O
.	O
</s>
<s>
The	O
content	O
,	O
padding	O
,	O
and	O
border	O
of	O
any	O
other	O
element	O
will	O
not	O
be	O
allowed	O
to	O
enter	O
this	O
area	O
unless	O
forced	O
to	O
do	O
so	O
by	O
some	O
advanced	O
CSS	B-Language
placement	O
.	O
</s>
<s>
Using	O
most	O
standard	O
DTDs	B-Language
,	O
margins	O
on	O
the	O
left	O
and	O
right	O
of	O
different	O
elements	O
will	O
push	O
each	O
other	O
away	O
.	O
</s>
<s>
The	O
above	O
section	O
refers	O
only	O
to	O
the	O
detailed	O
implementation	O
of	O
CSS	B-Language
rendering	O
and	O
has	O
no	O
relevance	O
to	O
HTML	B-Language
elements	O
themselves	O
.	O
</s>
