This site does validate, but so what?! It displays fine and everyone is happy, so why spent numerous hours on fixing ‘bugs’ such as adding missing ‘backslashes’ to < br > items. Pointless indeed.

You may have neglected to close an element, or perhaps you meant to “self-close” an element, that is, ending it with “/>” instead of “>”.

I march my own standard; a great article posted on mikeindustries.com tells you even more about the idea of invalidity.

For all lazy clickers, here an excerpt:

[...] this site renders my entire domain XHTML 1.0 Non-Compliant. Invalid. Erroneous. Whatever you want to call it. Here are the various crimes this one line of code commits:

* An ampersand is not properly encoded
* An alt tag is missing
* An attribute called ‘myfavoritetag’ is made up
* An attribute is missing quotes
* A script tag is missing its type and language attributes
* A non-closing tag is missing its trailing slash
* A tag is upper case? gasp!

By invalidating my entire site with this one line of code, I ensure that I am made aware the instant it matters. The instant this stuff starts to break anything in the real world, I will know. If I only had a few small errors on a few random pages around my site, I could easily miss the day when ?the big switchover? happens and wind up with broken pages I don’t know about. And since this code is in the form of a server-side include, I can freely remove it with a few clicks.

It’s kind of like carrying a canary down a mine shaft with you. As long as the canary is alive and chirping, you know you’re okay for air. Actually, I guess it’s not really like that.