A computer system is a group of linked devices that process, store, and input data and information. A computer network is a group of computers that are connected so that they may communicate with one another and share resources, data, and applications. A computer network's size can be classed. Local area network (LAN), personal area network (PAN), metropolitan area network (MAN), and wide area network (WAN) are the four types of computer networks (WAN). A local area network (LAN) is a group of computers connected in a small area, such as an office or a building. A Personal Area Network (PAN) is a network that is set up within a single individual and has a range of around 10 metres. A metropolitan area network is one that spans a greater geographical area. A metropolitan area network (MAN) is a network that combines many local area networks (LANs) to construct a bigger network that spans a broader geographical area. A wide area network (WAN) is a network that connects multiple states or nations over a large geographic area.