• A distributed system is a collection of autonomous computers linked by a computer network that appear to the users of the system as a single computer.

• From a system architecture perspective: The machines are autonomous; this means they are computers which in principle, could work independently

• From the user’s perception: the distributed system is perceived as a single system solving a certain problem (even though, in reality, we have several computers placed in different locations).

By running a distributed system software the computers are enabled to:
  - coordinate their activities

•   - share resources: hardware, software, data.

• Hence, Internet as such, is not a distributed system, but an infrastructure on which to implement distributed applications/services (such as the World Wide Web).