LAN/WAN/MAN
All three are different forms of the same thing (Network connections). A LAN is a local area network, which is usually used in the home or office where there are not many computers. MAN or Metropolitan Area Network is designed for a slightly larger geographical network such as a town or city. Finally, a WAN (Wide Area Network) is a data communication network that is larger than both the LAN and the MAN, an example of a WAN is the internet.

Server
Put simply a server is a host computer that holds information which can then be accessed by other computers on the network. Web hosts usually have large servers which can be accessed by people on the WAN network (The internet)

Protocol
Protocols are sets of rules that describe how data will be sent over the internet. The HTTP protocol for example shows the web browser how the information on the server will be shown and accesses.

Intranet
Pretty much like the internet that can only be accesses by the company, and is not on the internet. With it not being on the internet it is restricted to only people on the private network to access it. This will prevent any unauthorised visitors. Intranets are commonly used to share files internally.

Extranet
An extranet is a private network that uses internet protocols to restrict and prevent access to only authorised users. Most companies with extranets allows suppliers or people who might need to interact with the company access to their extranet.

Topology
A Topology is the physical and geometrical layout of a network. This shows exactly where and how things will be place on the network and in what order they will be connected. The most common topologies are the bus, ring and star.