Perl's @INC array is like the PATH environment variable for the shell program. Whereas PATH contains a list of directories to search for executable programs, @INC contains a list of directories from which Perl modules and libraries can be loaded.
When you use( ), require( ), or do( ) a filename or a module, Perl gets a list of directories from the @INC variable and searches them for the file it was requested to load. If the file that you want to load is not located in one of the listed directories, you must tell Perl where to find the file. You can either provide a path relative to one of the directories in @INC or provide the absolute path to the file.