A computer network, simply put, is a collection of computers and devices connected by channels that allow communication among users.  This enables the users to share resources with other users of the same network. There are many different types of networks.  The first computer network created in the world was for the Advanced Research Projects Agency Network (ARPANET) for the United States Department of Defense.  The basic designs began in 1960 with the development not beginning until 1969.
There are many reasons for utilizing a computer network.  When using a network, communications are often much faster.  Users can access email, instant messaging, etc.  A shared printer can be accessed by those users that are connected to the same network.  This is much more economic than each user having their own printer especially if they are only required to print occasionally.  One of the most important reasons to have users on a network is that they are able to share files and data which can be stored in an area on the network that all users of that network can access. 
Networks are classified into different groups based on the hardware and software that is being utilized to connect the components of the network.  Physical wiring or wireless technology can be used to connect the devices.  Hubs, switches, bridges and routers using an Ethernet would utilize the physical wiring to connect these devices.  A wireless local area network (LAN) is the utilization of radio waves or infrared signals to connect the devices.
The size of a computer network can help to determine the type of network which will most appropriately meet the user’s needs.  There a multiple different types of networks available, for example:  a personal area network would typically consist of a laptop or personal computer, printer, phone, scanner, and maybe a game console.  A local area network (LAN) is focused on a group of devices located in the same geographical location, such as an office building or school. A home area network (HAN) usually installed in the home connecting multiple computers and other digital devices.  A campus network is a computer network that is made up of multiple local area networks (LANs) within a limited geographical area, i.e. a college campus.  A wide area network (WAN) is a computer network that covers a large geographic area, i.e. a city or country.
The Internet is likely the most accessed network.  The governmental, academic, corporate, public and private computer networks, which are all connected.  The internet is a result of the ARPANET mentioned earlier in this article created by the US Department of Defense.  This, of course, is the basis of the World Wide Web.  An intranet is a set of networks which uses the same protocol an internet.  Most often, an Intranet is only open to certain scope of users.  These users are generally members of an organization where accessing this intranet is used to provide it’s users with company information or important communications not accessible by users outside the company.