From Microsoft:

Converters enable you to open files created by people using different versions of your Office programs. Find the appropriate converter for the version of the Office program on your computer.

Viewers enable people who don't have Office programs to see your work. Simply provide them with the appropriate viewer along with your files. These tools can be found from the Microsoft site:

Microsoft Office Converters and Viewers

Do you have some older Microsoft Works 6.0 files that won't work with Word and other Works versions? Check out this download: Microsoft Works 69 File Converter