Set of instructions is called software or programs. We can see and feel it. Software is divided into 4 types: Operating System or System Software, Language, Package and Application Software.
Operating System (OS) is an interface between the user and computer. Operating system starts the computer and computer accepts commands of programs when the operating system is loaded in the computer.
Language is a collection of predefined words. Computer languages are of 3 types:
- Low Level Language or Machine Language (It consist of 0s & 1s)
- Middle or Assembly Level Language (combination of both low and high level languages)
- High Level Language (Purley english like words)
Ex: Pascal, C Programming Language, C++, COBOL, BASIC, PROLOG etc.
Package is developed from a language. It is for some generalized particular purpose.
Application is developed from a package. It is for being applied. No further software can be developed from it. Application software means programs written for performing special kind of work with computer. Application software is usually made for the following commercial area: Games programs, word processing, spreadsheets, database management, invoicing and inventory.