Servers are generally very powerful computers containing lots of memory and storage space. They are typically found in corporations, universities, museums and other large institutions, although many small computer-related businesses also maintain servers. One server can connect to many clients. It obtains these resources whenever it communicates with the server. For example, when you surf the Web from your home or office computer, your computer becomes a client on the Internet network.
Communication involves both hardware and software.
On the hardware side, there needs to be a physical means of transmitting data. If the server and client are in the same building, data transmission often takes place directly, over a series of wires or cables that are placed throughout the building and which physically connect the computers together. This is known as a local area network. When data transmission occurs over the phone lines, modems are usually required to translate data from the digital format which it is used by the computer to the analog format that can be understood by the telephone system. A modem is the device which makes this translation.