If you look at the HTML 4 recommendation from the W3C, you'll find that this is not invalid HTML. SGML and HTML, unlike XML and XHTML, allow implicit opening an

If you look at the HTML 4 recommendation from the W3C, you'll find that this is not invalid HTML. SGML and HTML, unlike XML and XHTML, allow implicit opening and closing tags. As far as I know, they even allow overlapped nesting, which even breaks the tree nature of the document structure, e.g. <b>foo<i>bar</b>baz</i>. Browsers have supported this stuff since HTML 1, I seriously doubt there is any significant penalty in parsing. e.g. http://www.w3.org/TR/html401/struct/global.html#h-7.3 http://www.w3.org/TR/html401/struct/global.html#h-7.3