To performance a computer job by computer requires a number of instructions. The set of these is called “program”. Many short programs are combined for some defined needs and this concise set of instruction is called “Software”. Computer can only understand programs in machine language but we writes program in high level language. Each language has different language software. The computer software may be grouped as follows.
1.    System Software
2.    Application
3.    General Purpose
4.    Special Purpose