Internet Explorer (IE) is a nightmare for developers to design web pages for.
A classic example is our About page, the cogs will move in every other browser except when using Internet Explorer.
Here are a couple of common design problems with IE:
Square ends of buttons rather than it being curved in Firefox and Chrome
Font changes in IE vs Firefox.
Internet Explorer ???
Kogan, an online retailer, went so far as to add a surcharge of 6.8% for users of Internet Explorer 7. (http://www.kogan.com/au/blog/new-internet-explorer-7-tax/).
In comparison, Chrome and Firefox are free and have a lot better user and developer support. The user is actually able to see exactly what the developer wants them to see rather than bugs and common design problems.
Chrome and Firefox have the following in common which IE does not: