C

Intro
C is a cross-platform programming language, developed in 1972 by Dennis Ritchie at Bell Telephone Laboratories, made for use with the Unix operating system.
Sample Program
#include <stdio.h> int main(void) { printf("Hello World!\n"); return 0; }
C++
C++ is an extension to the C programming language. More on that here.
Useful Links
IDEs (Integrated Development Environments
Since C++ is backward compatible with C, C can be compiled with C++ compilers and IDEs.
IDEs that can be used with C include Bloodshed's Dev-C++ and Code::Blocks.