Some HTML1 closing tags are optional, i.e.:
</HTML>
</HEAD>
</BODY>
</P>
</DT>
</DD>
</LI>
</OPTION>
</THEAD>
</TH>
</TBODY>
</TR>
</TD>
</TFOOT>
</COLGROUP>
Note: Not to be confused with closing tags that are forbidden to be included, i.e.:
</IMG>
</INPUT>
</BR>
</HR>
</FRAME>
</AREA>
</BASE>
</BASEFONT>
</COL>
</ISINDEX>
</LINK>
</META>
</PARAM>
Note: xhtml is different from HTML. xhtml is a form of xml, which requires every element have a closing tag. A closing tag can be forbidden in html, yet mandatory in xhtml.
Are the optional closing tags
In other words, should I include them, or should I not include them?
The HTML 4.01 spec talks about closing element tags being optional, but doesn't say if it's preferable to include them, or preferable to not include them.
On the other hand, a random article on DevGuru says:
The ending tag is optional. However, it is recommended that it be included.
The reason I ask is because you just know it's optional for compatibility reasons; and they would have made them (mandatory | forbidden) if they could have.
Put it another way: What did HTML 1, 2, 3 do with regards to these, now optional, closing tags. What does HTML 5 do? And what should I do?
Some elements in HTML are forbidden from having closing tags. You may disagree with that, but that is the specification, and it's not up for debate. I'm asking about optional closing tags, and what the intention was.
1HTML 4.01
The optional ones are all ones that should be semantically clear where they end, without needing the end tag.
E.G. each <li> implies a </li> if there isn't one right before it.
The forbidden end tags all would be immediately followed by their end tag so it would be kind of redundant to have to type <img src="blah" alt="blah"></img> every time.
I almost always use the optional tags (unless I have a very good reason not to) because it lends to more readable and updateable code.