There are many different file formats on the web
One common problem with computers is the proliferation of different file formats. You have plain text files, word processor files, graphics flies, 3D graphics files and many other files types. It gets worse as you will find files in different word processing formats, different graphics formats and even different versions. For example, you won't just find Microsoft Word documents ... you will find different versions ... Office 97, Office 98, Office 2000, Macintosh and PC versions. All different. Sometimes you can read them and sometimes you cannot.
And there is little that is more frustrating than finally finding that graphic or document that you want, and then discovering that you cannot read it. What's worse is when you find the document for the CEO and you cannot find a converter to let him read it. So now he's mad at you.
Many programs offer built-in conversions. Microsoft Word 97 and Excel 97 included something called the ValuePak, which added on additional converters. This can help but not solve the problem.
The absolute best solution that I've found is called "Conversion Plus", a product written especially to handle this problem. It has hundreds of converters and lots of other features that make it ideal. It's well worth the expense if you are doing any kind of cross-platform work at all. The thing that I liked best was how transparent it is. You just install the product, and then it "knows" what's what and you generally don't have to worry anymore.