A server is a host computer on the network that stores information and performs critical functions for a particular purpose.

Examples of types of server:

• File server - General data and file storage.
• Print server - . Management of print queues.
• Web server - Storage and availability of web documents.
• E-mail server - . Directs email to the appropriate destination.
• Backup server - . Provides redundancy by copying the contents of another server.
• SQL server/Database server - Provides access to database files.

The operating system is the single most important programme on a computer and provides a platform to run applications. The most popular PC operating systems are: DOS, Mac, Windows and Linux.

Essentially an operating system has two primary functions:

• Management of the computer's hardware and software resources eg processor, memory and disk space.
• A stable, consistent method for applications to communicate with the computer hardware.