LIB file is used in Microsoft systems. The file is generated with LINK file which is used to save objects, resources, standard LIBraries, command input and module definitions.

The compilation of LIB file is done along with other files for creation of standard LIBraries and import LIBraries. These LIB files are used to resolve external references by LINK by looking into the command lines and then in default LIBraries. Standard LIBraries with the extension of LIB are used to store objects. The import LIBrary file is used to store information related to exports in other programs. These import files are created when a program is built containing exports.