GLib began as part of the GTK+ project. However, before releasing GTK+
version 2, the project's developers decided to separate non-GUI-specific
code from GTK+, thus creating GLib as a separate software bundle. GLib
was released as a separate library so other developers, those who did
not make use of the GUI-related portions of GTK+, could make use of the
non-GUI portions of the library without the overhead of depending on the
entire GUI library.

Since GLib is a cross-platform library, applications using it to
interface with the operating system are usually portable across
different operating systems without major changes.