Believe it or not, the communication in any way it is, is the most important for the human existence. Can you imagine the human relationship or even the entire humanity without the communication? It is really important because through this way we can express our feelings, our intentions, our personality, we can exchange information, etc.

There are two important streams in the communication networks which is data communication ( which refers to the computer network, the communication between 2 computers) and telecommunication which refers to the human – to – human communication through the global telephone system, only due to some historical reasons exists a difference between these two.  More then ever, the data communication is relying on the telecommunication networks and telecommunication networks on the computer technology. They are convergent.

Types of networks and network topologies :
- network components
- active network components
- the diagram of a network (LAN) interconnected WAN
- repeater
- hub
- bridge
- switch
- router

A network is an infrastructure which allows two or many more computers – called hosts – to communicate to which other.

So, the computer network is a :
-         set of computers (stations)
-         interconnected through communication media (cable, optic fiber, telephone, radio)
-         for sharing by many users, resources
-         physical (hardware)
-         logical (software operating systems and applications), and
-         information (databases, files) associated to the other computer networks.

The computers networks were at first local networks.

- as a characteristic of today, it is a global public network which is becoming a part of human existence at all the levels.
- what made this globalization possible was the acceptance of some standard protocols of communication and concepts of natural existence, such as open systems and delegating the responsibility on the hierarchical tree of the network.

A network or a communication protocol is a set of rules for communication and the work between computers network. The protocol provides that two completely different products to communicate and work together. More abstract, a protocol is a way defined by the transfer data between the distributed stations. It defines an interface ( a clearly separation between different entities) for the distributed scenarios thru which are described the possible interactions and data – exchange components.

Corresponding to the enormous variety of types of communication and their levels of interaction in the network, exists also, a big number of protocols:
-         Ethernet – is the based protocol for the physical networks (cabling, interface)
-         TCP/IP – is a set of protocols underlying the entire Internet infrastructure, but also of the most local networks.
-         HTTP – web, documents
-         POPs / SMTP – electronic emails
-         FTP – file transfer
-         NNTP – news
-         NTP – network time synchronization
-         DNS – award of the domain name