Communication structures refers to the layout of the existing communication groups and channels. We would like to introduce the four best known types of these layouts: point-point: this is the most straightforward. It only involves two participants. It may be ’simplex’, which means that only one of the participants 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 in order to communicate with each other. Nowadays modern routers and Wifi works in this way. Bus structure: the participants have to send their messages through a shared channel (bus). Only one participant can send message at a time; the others have to wait until the transmission is complete. Tree structure: almost the same as a bus structure, but the whole layout consists of hierarchy levels as well. Of course mixed configurations are also well-known in these communication layouts. {{:tanszek:oktatas:techcomm:information_-_basics:pasted:20231026-201747.png}}