The five viewable fonts are:

• Arial | Georgia | Times | Verdana | Courier

Also, when putting this brief list together, I asked Dan Crook (head of design at Solutions Four Impact Limited) for his thoughts on the issue. His reply is pasted below:

“ . . . another point is operating systems & browsers render fonts in different way – Mac osx renders them beautifully – hence why it the preferred system for designers, artists etc. – older windows os make fonts look all pixelated, as did Vista & Windows 7, but I think this has been addressed now.”

But I have seen websites with different fonts in – why is this?

The website you have seen has been probably created in Flash, or contains Flash elements. In addition, you may have been looking at an image (jpeg or gif).

Either way, if you want your site to appeal to search engines and be as accessible to as many browsers as possible, keep to the five fonts we have mentioned.