Communication structures refer to the layout of the existing communication groups and channels.

We would like to introduce the four best known types of layouts:

• Point to Point: this is the most straightforward. It only involves two participants. It may be ’simplex’, meaning that only one participant communicates (therefore the process is only a one-way process). It may be ’full-duplex’, which means that the communication partners can equally send information to each other (for example Skype, or Hangouts where the participants can talk simultaneously).

• Star-structure: In this case, the whole process is controlled by a main unit, and the other participants have to use this main unit to communicate with each other. Nowadays, modern routers and Wi-Fi work in this way.

• Bus structure: The participants send their messages through a shared channel (bus). Only one participant can send a message at a time; the others must wait until the transmission is completed.

• Tree structure: almost the same as a bus structure, but the whole layout also consists of hierarchy levels.

Of course mixed configurations are also well-known in these communication layouts.