What Network is
The term actually has many different meanings depending on the person, company, or context in which it is being used. Basically, it is a collection of two or more computers and associated devices that are linked together with communications equipment. Once connected, each part of the network can share the software, hardware, and information contained in the other parts.
The most common types of network are LANs (Local Area Networks, in which the computers share the same office space, room, or building) and WANs (Wide Area Networks, in which LANs are connected at different geographic locations by telephone lines or radio waves, as in wireless communications). Network connections are established by twisted-pair cable, coaxial cable, fiber-optic cable, connectors, or NICs (network interface cards). Network computing depends on protocols that work with a variety of operating systems and network hardware (see: IEEE and ISO). When you hear someone talking about "sharing network resources," they are referring either to client/server networks or peer-to-peer networks.
Also, you may hear Internet companies refer to their "network of Web sites," a group of associated sites that's analogous to a television network or cable TV network. If you have a small business that uses a network for Internet access and file sharing, be sure to have a firewall installed, to protect yourself from unauthorized access.
The meaning of Server
A host computer on a network. It houses information and responds to requests for information (for example, it houses Web sites and executes their links to other Web sites). The term "server" also refers to the software that makes the act of "serving information" possible. Commerce servers, for example, use software to run the main functions of an e-commerce Web site, such as product display, online ordering, and inventory management (you'll also hear this described as shopping cart technology). A server is the control computer on a LAN, meaning it controls the software, access to printers, and other parts of the network (usually accompanied by workstations that "share the load"). A server may be dedicated (where its sole purpose is to be the server) or non-dedicated (where in addition to being the server, it can be used for basic computing purposes).