Networks are systems that are formed by links. For example, roads that connect groups of people together create a physical network. Connections with your friends create your personal network. Websites that allow individuals to link to each other’s pages are called social networking sites.

People use the following networks every day:

Networks share information and use various methods to direct the manner in which information flows. The information on the network goes from one place to another, sometimes via different paths, to arrive at the appropriate destination. For example, the public transportation system is a network similar to a computer network. The cars, trucks, and other vehicles are like the messages that travel within the network. Each driver defines a starting point (source computer) and an ending point (destination computer). Within this system, there are rules such as stop signs and traffic lights that control the flow from the source to the destination. A computer network also uses rules to control the flow of data between hosts on a network.

A host is any device that sends and receives information on the network. Some devices can serve either as hosts or peripherals. For example, a printer connected to your laptop that is on a network is acting as a peripheral. If the printer is connected directly to a network, it is acting as a host.

Many different types of devices can connect to a network:

Computer networks are used globally in businesses, homes, schools, and government agencies. Many of the networks are connected to each other through the Internet. A network can share many different types of resources and data:

Network devices link together using a variety of connections: