HTML and spell checking are standard features in quality web design software, but unfortunately many designers don't take the time to test every page they make. In the case of HTML errors, it is often the case that the designer does not know HOW to fix them!
In our opinion, if they call themselves a professional, they should know how and fix all their mistakes before a page ever gets published on the World Wide Web. Sometimes, it is actually the web design software they use that adds in incorrect or superfluous code.
Many people do not realize that Microsoft's Front Page is among the WORST web design programs. It appears that program is designed to make pages look good only on Internet Explorer, but at the expense of other competing browsers.
If this was a part of Microsoft's strategy to gain browser market share, you must admit it worked. It, in effect, made all who use Front Page an unwilling partner (with Microsoft) in the "browser wars". Some web designers brag that they use Front Page. To us, it says they don't know any better.
How many errors are in your HTML/XHTML and CSS? You will be surprised!
If you've got a web site now, click to Validate your entire site at once! (100 page limit)
The W3C buttons on this and every page on this site can be used to validate any page. They also offer a way to validate web pages BEFORE they go on the net, by checking HTML code from offline files on any hard disk drive. We run many tests on every page!