In computing, a server is a piece of computer hardware or software (computer program) that provides functionality for other programs or devices, called "clients". This architecture is called the client–server model.

A client–queue–client or passive queue system is a client–server computer network in which the server is a data queue for the clients. Instead of communicating with each other directly, clients exchange data with one another by storing it in a repository (the queue) on a server.

client-server

double-ended queue

HTTP server

A web server is computer software and underlying hardware that accepts requests via HTTP (the network protocol created to distribute web content) or its secure variant HTTPS. A user agent, commonly a web browser or web crawler, initiates communication by making a request for a web page or other resource using HTTP, and the server responds with the content of that resource or an error message.

<algorithm> /dek/ (deque) A queue which can have items added or removed from either end[?]. The Knuth reference below reports that the name was coined by E. J. Schweppe. [D. E. Knuth, "The Art of Computer Programming. Volume 1: Fundamental Algorithms", second edition, Sections 2.2.1, 2.6, Addison-Wesley, 1973]. Silicon Graphics (http://sgi.com/tech/stl/Deque.html). [Correct definition? Example use?] (2003-12-17)

<programming> A common form of distributed system in which software is split between server tasks and client tasks. A client sends requests to a server, according to some protocol, asking for information or action, and the server responds. This is analogous to a customer (client) who sends an order (request) on an order form to a supplier (server) who despatches the goods and an invoice (response). The order form and invoice are part of the "protocol" used to communicate in this case. There may be either one centralised server or several distributed ones. This model allows clients and servers to be placed independently on nodes in a network, possibly on different hardware and operating systems appropriate to their function, e.g. fast server/cheap client. Examples are the name-server/name-resolver relationship in DNS, the file-server/file-client relationship in NFS and the screen server/client application split in the {X Window System}. Usenet newsgroup: news:comp.client-server. ["The Essential Client/Server Survival Guide", 2nd edition, 1996]. (1998-01-25)

Client-server model is a distributed application structure that partitions tasks or workloads between the providers of a resource or service, called servers, and service requesters, called clients. Often clients and servers communicate over a computer network on separate hardware, but both client and server may reside in the same system.

Messages Server is a component of OS X Server from Apple Inc. It was first introduced as iChat Server with the release of Mac OS X Server 10.