What is a network service?

A network service is an application running at the network application layer. The function of network service is to provide data storage, manipulation, presentation, and communication capabilities with a client-server or peer-to-peer architecture based on application layer network protocols.   Each service is usually provided by a server component running on one or more computers and accessed via a network by client components running on other devices. However, the client and server components can both be run on the same machine.