Inside the World of Computing

2Computer Networks and Their Applications

2.1. Introduction

Communication is an essential aspect of life for all species, both within (human to human) and between them (human to animal, human to plant, etc.). This communication can concern two actors, one actor and one group, several groups, etc.

We will limit ourselves to communication centered on the transmission of information, as defined in Chapter 1.

Communicating information involves several elements:

• – the sender: the entity that sends a message. In this chapter, it will generally be computer equipment;
• – the receiver(s): the entity/entities receiving the message;
• – the message: an element that carries information of any kind. This message is transmitted from the sender to the receiver(s);
• – the channel: the path through which the message will circulate, between the transmitter and the receiver. This channel can be a cable, the air, etc.;
• – the code: the language in which the message is formulated. This language must be understandable, or translated to be understandable by the receiver;
• – a protocol: this ensures the correct organization of the transmission. In a telephone conversation, not everyone speaks at the same time;
• – other elements such as the identification of the actors, confidentiality conditions, etc.

We are entering a complex world of hardware, algorithms, software, conventions, etc., and we have to deal with a lot of different things. This world fascinates many research teams, whether in universities ...