Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A telecommunications network is a network of telecommunications links and nodes arranged so that messages may be passed from one part of the network to another over multiple links and through various nodes. Telecommunications network links (including their endpoints or "nodes") may in turn be built out of hierarchical transmission systems. All telecommunication networks are made up of five basic components that are present in each network environment regardless of type or use. These basic components include terminals, telecommunications processors, telecommunications channels, computers, and telecommunications control software.