Validate Early, Validate Often
With the release of IE7, there has been a lot of talk regarding web standards. In particular, IE7 is more web standards compliant than previous versions. This is of concern because prior versions of IE are very forgiving regarding the sins of invalid HTML. Sites that work perfectly well with prior versions of IE could very well look poor when viewed with IE7.
This is not a new problem. Testing with multiple browsers has been a mainstay for years. It is still required. While two browsers may be standards compliant, that does not mean that the browsers interpret the standard the same way.
A starting point, however, is to make sure the site is compliant with the version of HTML that it has been developed to… (Not sure what version? — that is probably indicative of a problem. Ask the development team which version of HTML / XHTML that they support…) The W3C offers a validation service, http://validator.w3.org, which allows the user to submit a URL or the page source.
Now, I had used this in the past but was not rigorous about. It was a pain to save a page to a file then upload it to the validator for any server not on the internet or if the page required a login. I usually would validate a page if it was having problems, otherwise I would assume it was OK. The firefox extension, Web Developer by Chris Pederick, makes validation a breeze. From the tools menu on the Web Developer toolbar, select “Validate Local HTML”. The extension will take care of saving the currently loaded page to disk and uploading it to the validator. The results of the validation are displayed in a separate tab.
I recently went through an exercise of submitting a bunch of pages to the validator. While it did not find anything major, it did find some stray characters in the HTML sources and pointed out some attributes that are not in the standard. Nothing that keeps me up at night but one less thing to nag at the back of my mind.