If you're using these libraries for your projects, you propably need to install the -devel versions from your distribution's repository.

libc - the Standard C Library

The C library is part of the C standard and contains functions such as printf() and malloc(). It is linked with -lc, but that's default and you don't need to provide this parameter.

The most important (okay, for open source programmers) implementation is the GNU libc (glibc). Don't confuse the glibc with the glib (described further below).

math

The math library contains functions more advanced than a simple calculator (think scientific calculator, but see also the GNU Scientific Library, further below).

Unlike the standard C library, the math part must be linked explicitly with -lm.

POSIX threads

Threads are multiple paths of execution inside a process that share its address space. Long running tasks can be delegated to threads to avoid blocking the main process. On today's multi-processor systems, they can be executed concurrently to speed up things. But in any case, the synchronization, especially for access to shared resources, must be taken care of manually.

Link with -pthread or -lpthread.

Gnome universe

glib

This is a part of GTK+ providing basic functionality Gnome is based on.

gobject?

GTK+

The object-oriented widget library, that makes the Gnome GUI and many other programs.

GNU Scientific Library

t.b.d.