The first library that we'll discuss here is the glibc library, which is designed for performance, compliance of standards, and portability. It was developed by the Free Software Foundation for the GNU/Linux operating system and is still present today on all GNU/Linux host systems that are actively maintained. It was released under the GNU Lesser General Public License.
The glibc library was initially written by Roland McGrath in the 1980s and it continued to grow until the 1990s when the Linux kernel forked glibc, calling it Linux libc. It was maintained separately until January 1997 when the Free Software Foundation released glibc 2.0. The glibc 2.0 contained so many features that it did not make any sense to continue the development of Linux libc, so they discontinued their fork and returned to using glibc. There are changes that are made in Linux libc that were not merged into glibc because of problems with the authorship of the code.