HTML Basics
Stanford University Libraries & Academic Information Resources

Double/Single quoting the value of attributes

Ok, this was an out and out lie, and people who follow links deserve to be told the truth. The rule really says that if the attribute value consists entirely of what are known in SGML jargon as NAMECHARs, then you don't need to put quotes around it.

Thus

    <hubcap brand=Chrysler>

would be perfectly legal.

Now please don't ask me which characters are NAMECHARs. I can never remember, and neither can a lot of other people. That's why it's a good habit to put all attribute values in single quotes, even when you don't need to. To be fair, lots of SGML experts disagree with this, but I say, it couldn't hurt, eh?