Recognizing these files extension is not essential to your use of Netscape but when you start downloading files for use on your computer system you will need to know if the file is usable on the system. You need to be aware what will and what won't work on YOUR system. Learning file extensions may provide you with a better understanding of the material you are viewing or are about to view. Also .qt extensions. Compressed files are those that have been shrunk in size in order to take up less space and provide for a faster transfer between computers.
Archived files are series of files compressed into one file name.
In order to use these files you need a program that can uncompress them back to their original format.