We have to define some key terms for better understanding of our subject. These information are data which compose from characters such as the letters of the alphabet, numbers, punctuation marks and other symbols. With the term Data Communication we mean the exchange of information under the form of data between Data Terminal Equipment. Terms Talking about our days, when we are referring to the term computer connectivity we have a complex of hardware, software and physical appliance, and we mean the way and how computers can communicate and share common sources with the use of an intelligent or common network. Also the evolution of the voice communication has created an extensive telephone network which today covers a very large part of the planet, and computers have taken advantage of that network in a great rate so as to satisfy their needs for data communication. After the decade of the 1950 the computers started developing, and the communications started playing an important role in peoples life. From the time that electricity and electronics had developed there was rapidly changes at the section of the communications. The network first developed for the need of the voice communication but after the appearance of data communications need the same network was used. So imagine that he has X friends, he would need X(X-1)/2 lines and X-1 phones, that was impossible so the need of networks come up. He was talking with a friend of his with a single line, but later when he wanted to talk to another friend of his he needed to use another line to connect his phone and the phone of his friend. The need for networks appears for the first time when Graham Bell set in use the telephone. Also the transfer speed of the information was small, the size of the information tiny and the security of the communication was almost absence. But these ways of communication was neither accurate nor has the certainty of the success. The signals of smoke, the sounds of the drum, the fire were some of the basic ways for the transfer of a message in a era years ago. As we can see from the history there was a huge try to achieve the communication between people. Networks and Connectivity ByGeorge Vagenas Trying to give a definition to the term COMMUNICATIONS we can say that Communications is the dispatch of a message from one point to another and the confirmation of the complete, right and conceivable receiving of the message by the authorized addressee. Networks And Connectivity Essay, Research Paper