syntax - Is it correct to use single quotes for HTML attributes?

Question

Recently I've been seeing a lot of this:

<a href='http://widget-site-example.com/example.html'>
    <img src='http://widget-site-example.com/ross.jpg' alt='Ross&#39;s Widget' />
</a>

Is it valid to use single quotes in HTML? As I've highlighted above it's also problematic because you have to escape apostrophes.

Answer 1

It's certainly valid to use single quotes (HTML 4.01, section 3.2.2). I haven't noticed such a trend, but perhaps there's some framework that powers web sites you've visited that happens to quote using single quotes.