| By definition a network is a group or system that | | | | office are in a LAN, however, the New York office |
| interconnects components together. A network of | | | | also connects to an Office in Chicago who hosts ten |
| retail stores, for example, implies some sort of | | | | other computers. All together, that network is said to |
| relationship between the stores. A railroad network | | | | be a WAN spanning New York to Chicago. But |
| suggests that the tracks interconnect at different | | | | individually each office is a LAN in its own right. One |
| points. And a computer network interconnects | | | | LAN in New York and one LAN in Chicago. This is |
| computers. | | | | why we say that strictly speaking a WAN |
| By far the most famous computer network in the | | | | interconnects LANs. |
| world is the Internet. The Internet is, in fact, a | | | | A description of how the network is wired together |
| collection of smaller networks that are interconnected | | | | can be provided using a physical network topology. |
| together - a network of networks if you can imagine | | | | Network topologies are used to describe the |
| that. | | | | different ways to connect computers together. A |
| But computer networks don't necessarily have to be | | | | bus topology, for example, describes computers |
| large or complex. By definition, the smallest possible | | | | connected across a common wire in a linear fashion. |
| computer network would include just two | | | | A star topology describes computers connected to a |
| interconnected computers. The interconnection can | | | | common central device such as a switch. Other types |
| be achieved using a cable or by wireless technology. | | | | of common topologies include ring topology as well as |
| Whatever the medium, as long as the computers can | | | | mesh and partial mesh topology. |
| communicate together they are part of a network. | | | | But possibly the most important working components |
| Surprisingly, the Information Technology industry | | | | of a computer network are the protocols. A protocol |
| doesn't define networks by size, rather, by location. | | | | is a set of rules. In order to communicate correctly, |
| Computers that are interconnected in a small | | | | computers must talk the same protocol so that they |
| geographical location such as a home or an office are | | | | understand what is being received and know how to |
| said to be in a LAN (Local Area Network). A LAN can | | | | send information in return. The IT industry has |
| have two computers or two thousand computers. | | | | successfully established TCP/IP as the dominant |
| Conversely, computers that are connected across a | | | | network protocol across the world. The |
| wide geographical area such as between cities or | | | | standardization of TCP/IP in computers has allowed |
| countries are said to be in a WAN (Wide Area | | | | the internet to thrive because is provides a common |
| Network). Strictly speaking a WAN actually | | | | language that computers can use to communicate |
| interconnects LANs. Five computers in a New York | | | | with each other. |