This page is designed to tell commercial web developers why they should develop StandardsCompliant web pages.

Why should I make my web site compliant?

Because the IT department of your biggest clients are changing away from InternetExplorer in droves. Windows users tend towards MozillaFirefox or Opera, Mac users may be using MozillaCamino or Safari. Linux users have probably been using Mozilla forever.

The percentage of people using a non-IE browser is estimated to be between 5% and 15%, depending on who you ask. You wouldn't tolerate a phone system or secretary that turned away 10% of potential customers who ring you...

Dos and don'ts

• Don't create browser detection pages that lock out browsers you think won't work, or browsers you don't recognise. New browsers and versions come out all the time, and you never know when one of them will be fixed.
• Don't use markup purely because its default display suits what you want. Use markup that's suitable to the content, then style it using CSS, instead.
• Don't test your CSS padding/margin/width settings by only testing in IE.
• Do test your HTML pages against http://validator.w3.org/ (or the free sgmlnorm program).
• Don't put stuff in a table without <td> tags around it (IE displays it, Mozilla might not).

• Don't put tooltips in the alt attribute. They belong in title.

  Put an empty alt attribute on your images as a rule of thumb. Only contain when the image actually replaces part of a sentence or is otherwise part of the text should the alt attribute contain any text, which should be what the image replaces. Imagine your content being read aloud: would the content alt attribute make sense as part of the text? If not, its alternative text should be empty. This means decorative and even illustrative images should not containt alternative text.

• Be careful with your comments:

  • Don't use <!-- and --> in <script> tags without making sure they are matched. InternetExplorer won't care, but Mozilla will consider the rest of your page commented out.

  • The popular <!----------> style "separators" are dangerous. With an odd numbers of dashes, the comment does not close, so the rest of your page will be commented out. Best to avoid any more than single dashes altogether inside comments.

    (Actually, <! ... > is a declaration, and --...-- inside a declaration is a comment. So, putting -- inside it actually closes your comment, and another -- starts a new comment. So only use double dashes at the start and end of the comment!)

• Don't use document.all in your JavaScript
• Don't use MSXMLDOC

See a great guide on the specifics and the Mozilla Web Author FAQ.

Should I support Netscape any more?

If you support Mozilla, you're supporting Netscape 7 and up. These days it's realistic to drop support for any version of Netscape 4 or below.