A distributed system uses  a number of different computers linked by a network. The user will feel that he is only using one local computer.

Eg A user on Computer A can run a program on Computer B which uses data stored on Computer C.

There are several Internet-based schemes which use a computer's off-time to perform some processing. Examples include the SETI (Search for Extra-Terrestrial Intelligence) and the Distrubuted.net project.

Eg Military command and control; Airline System;

A distributed database stores data on a number of different computers linked by a network. The DBMS (Database Management System) manages all queries and processing of distributed data. Elements of the DBMS would be stored on all computers in the system.

Advantages:

• Large databases can be shared out between a number of computers.
• Improved performance as a single computer is not overloaded with processing requirements.

Disadvantages:

• data queries may fail if one of the computers in a distributed system is faulty
• data consistency may be a problem if data is stored on a number of different machines.