The network term is extremely wide covered because it's used in almost all the domains that have connection to computers and devices with Internet. For example, networking can be explained as the connection between 2 or more computers. A simple network can be established between two computers and it's called a LAN (Local Are Network). The computers communicate between them with the help of hardware devices called network adapters (PCI cards or build-in motherboard modules). The Internet is actually a gigantic network where everyone is connected. The Intranet is a multitude of computers and devices that are operating outside the Internet zone where Data is accessible only from the inside (mostly encountered in companies).
For more information, Wikipedia's entry will provide everything you need to know.
