Some browsers are more forgiving of incorrect code than others but just because something displays OK on your screen, it doesn't mean that others will see the same thing - check your site on as many different machines and browsers as possible.

It is worth being as strict as you can with your code: writing correct syntax will increase the chance of a site doing well on a wide range of browsers and go some way to 'future proofing' the site against new standards.

If you're working with a text editor it's especially important to validate your code for errors. Many editors come with built in tools for checking your pages, but run your pages through a third party validator to make sure.

One of my favourite utilities is HTMLValidator (PC only), which reports on any syntax errors in your code, offering handy tips and related links.

Although it's technically not a fully fledged validator, it's proved to be a real life saver for many authors, particularly when trying to work out why a complex page isn't displaying properly. A more thorough validator can be downloaded from www.arealvalidator.com

Link checkers. It's vital to make sure that all the internal and external links within your site are working as nothing drives a surfer away quicker than a few '404 page not found' messages.

For small sites it's an easy task to check them online by simply clicking on every link you can find, but for larger sites sophisticated commercial programs like Linkbot could prove a worthwhile investment. Xenu Link Sleuth is a capable free alternative, or you can try the online tools listed opposite.