Following are the three important as well as main components of Computerised Accounting System :

1. Hardware,
2. Software and
3. Human ware.

1. Hardware : Hardware refers to the physical elements of a computer. This is also sometime, called the machinery or the equipment of the computer. Example of hardware in computer are the Central Processing Unit (CPU), Keyboard, Monitor, Mouse, DVD drive, Pen drive, Printer, Sound card, Speakers, etc. These components of computers are also classified as Input devices, CPU and Output devices. Mouse, Keyboard, Touch screen, Bar code reader, etc. are included in Input devices. While Central Processing Unit (CPU) is known as brain of computer as it does all calculations, logical decisions and controls activities of machine. CPU comprises of control unit, memory unit and arithmetic and logical unit. While output devices comprises of Monitor, Printer, Speaker, etc.

2. Software: Software is a general term for the various kinds of programmes used to operate computers and related devices. In other word, computer programmes which are needed to get the work done through the various parts of computer is known as software. Software can be divided mainly into two categories : (1) System software and (2) Application software. System software is used to control the operations and to extend processing capability of a computer system. While Application software is used by users to perform specific functions. For example, Windows 7 is system software while Tally is application software.

3. Humanware : The word Humanware is used for the people, who work with computer and software, e.g., programmers, data entry operators, software engineer, hardware engineer, system analyst, etc. These people also play an important role in effective implementation of computerised accounting system.