 Since source is designed to be copied from gnulib, it is not a library per-se, as much as a collection of portable idioms to be used in other projects.Making a software package work on a system other than the original system it worked on is usually called "porting" the software to the new system, and a library is a collection of subroutines which can be added to new programs.Thus, Gnulib is the GNU project's portability library.