A network is a connected system of objects or people. The most common example of a network is the telephone system, which is widely known as the Public Switched Telephone Network (PSTN). The PSTN allows people in virtually every corner of the world to communicate with anyone who has access to a telephone.
A computer network works similar to the PSTN. It allows users to communicate with other users on the same network by transmitting data on the cables used to connect them. A computer network, as illustrated in Figure , is defined as having two or more devices such as workstations, printers, or servers. These devices are linked together for the purpose of sharing information, resources, or both. Network links are made using copper cables, fiber-optic cables, or wireless connections. Wireless connections use radio signals, infrared technology (laser), or satellite transmissions. The information and resources shared on a network can include data files, application programs, printers, modems, or other hardware devices. Computer networks are used in businesses, schools, government agencies, and even some homes.
It is important to understand that networks are multilayered. A network consists of many overlapping layers such as cabling systems, addressing schemes, and applications. The layers work together to transmit and receive data. The Open Systems Interconnection (OSI) reference model, which was created to define these multiple layers, is illustrated in Figure .
The OSI reference model and the different ways in which computers can be networked in order to share resources are discussed later in this module.
A computer network works similar to the PSTN. It allows users to communicate with other users on the same network by transmitting data on the cables used to connect them. A computer network, as illustrated in Figure , is defined as having two or more devices such as workstations, printers, or servers. These devices are linked together for the purpose of sharing information, resources, or both. Network links are made using copper cables, fiber-optic cables, or wireless connections. Wireless connections use radio signals, infrared technology (laser), or satellite transmissions. The information and resources shared on a network can include data files, application programs, printers, modems, or other hardware devices. Computer networks are used in businesses, schools, government agencies, and even some homes.
It is important to understand that networks are multilayered. A network consists of many overlapping layers such as cabling systems, addressing schemes, and applications. The layers work together to transmit and receive data. The Open Systems Interconnection (OSI) reference model, which was created to define these multiple layers, is illustrated in Figure .
The OSI reference model and the different ways in which computers can be networked in order to share resources are discussed later in this module.
