the essential components of an information system

1. Hardware
• The term hardware refers to machinery. This category includes the computer itself, which is often referred as the contral processing unit(CPU), and all of its support equipments. Among the support equipments are input and output devices, storage devices and communication devices.
2. Software
• The term software refers to computer programs and the manuals that support them, Computer programs are machine-readable instructions that direct the circuitry within the hardware [arts of the CBIS to function in ways that produce useful information from data. Programs are generally stored on some input and output medium often a disk or tape.
3. Data
• Data are facts that are uised by programs to produce useful information. Like programs, data are generally stored in machine-readable from on disk or tape until the computer needs them.
4. Procedure
• Procedures are the policies that govern the operation of a computer system. "Procedures are to  people what software is to hardware" is a common analogy that is used to illustrate the role of procedures in a CBIS.
5. People
• Every CBIS needs people if it is to be useful. Often the most over-looked element of the CBIS are the people, probably the component that most influence the success or failure of information system.