PAK files are usually used by various games to contain or store information needed during the installation and when the game is played.
These files are simply built and are usually a unencrypted header file and a file table which contains information regarding the files and the actual files themselves.
In some cases the files and the file table are encrypted.
Examples of games that use the .pak file extension are.
» Final Fantasy
» Quake II
There are a number of programs available such as PakViewer which allow you to edit .pak files these are usually used to create modifications and addon for the games in various gaming communities.
» PakViewer 1.0
How to open .pak files?
Software to open .pak files
What are .pak files