Some programs such as the first one are complete in one file while others like the second one use several files. Usually the first file in the set is the one that loads or 'boots' the program. Relative files are used primarily for database applications. These are by far the hardest files to copy, and you must use a special copier to move them from disk to disk. Validating a disk can cause problems to these files.
Commercial programs use random files a lot.
This wild card can be used in place of a character it stands for any character. You can use it in a directory to look for all the files that include something. This one will allow you to locate a certain 'type' of file. Wildcards are not allowed when renaming or saving files. Sometimes when my drive gets too hot I have to use it in order to get the drive to save my programs.