Internet has meant the biggest revolution ever in telecommunications. Internet is a wonderful resource for information, knowledge, entertainment, discussion... Since the development of its use, it has changed the daily-life of millions of users all over the world, who use it for e-mails, chats, world wide webs (www)... In fact, you wouldn't be reading this right now without the Internet. But did the Internet suddenly appear? What do you know about its history? And how does the Internet really work?
A computer net is a connection between different computers which allows us to exchange information, share a common software or hardware, etc. Internet is a group of linked computer nets (in fact, the word "Internet" comes from Interconnected Networks.
· Brief History of the Internet
If you want to learn a bit more about the history of the Internet, you should watch this video:
Internet was at first created as a proposal of the Defense Department of the USA. In the 1950's the agency ARPA (Advanced Research Projects Agency) was asked to create a strong communications net which would remain operative under any conditions. In 1966 Lawrence G. Roberts created ARPANET, a wide-area communication net for computers and by 1969 he was able to connect four computers to this net at the same time. During the 1980's they were developed several nets of computers which, together with the already mentioned ARPANET, contributed to the creation of the protocol of communication TCP/IP, which we will explain later. As time went on, the number of users and nets that were connected to ARPANET highly increased. This led to the creation of NSFNET, a net that integrated the rest of the small nets. By 1990 ARPANET disappeared, leading to the apparition of Internet.
· How does the Internet really work?
During the development of the Internet, they were several key concepts that allowed its success. One of them was Packet Switching. Packet Switching means that the complete message or information is divided into different portions, each of them travelling to the destination computer by different routes. By using this system, we improve the communication nets' flexibility. One of the other key concepts we mentioned, was the creation of a protocol of communications, that is to say, a "universal agreement" which is adopted in order to allow and guarantee communication between completely different devices. This protocol was the TCP/IP:
-TCP: Transmission Control Protocol. It divides the messages into different packets, codes them and adds some information in order to reorganize the information after it has reached its final destination.
-IP: Internet Control. It drives the packets inside the nets and identifies the computers by using the IP directions.
IP directions are made up by four octets of numbers and are used to identify unequivocally each host (a computer connected to the Internet). Each host receives a unique IP direction, which identifies at the same time the net the computer belongs to and, inside that net, the computer itself.
Although all IP directions are made up by 32 bits, not all the nets are of the same size. In order to solve this new problem, they were created different kinds of nets, according to the number of computers that each net could connect. The Net Mask -a number of 32 bits- was then created in order to differentiate the diverse nets. The role of this Net Mask is to indicate the devices which fragments of the IP direction of the computer identifies the net the computer belongs to, and the fragments which represent the computer itself inside the net.
Up to now, we have been talking about the IP directions and their uses. However, whenever we are surfing the Internet, we use Domain Names instead of directly using IP directions. Domain Names are words separated with full stops which identify and indicate us the position of a computer or host inside its net. This concept is similar to the idea of IP, so Domain Names are mainly used because it is easier to remember, for example, www.google.es than its matching IP: 66.102.11.104. The DNS (Domain Name System) is a data base which turns Domain Names into IP directions and vice verse.
· How can I connect the Internet?
Up to now, the most used communication lines used to connect the Internet have been the telephone lines. However, nowadays they exist different ways to connect the Internet, such as the optical fiber lines. Depending on the kind of line we have, we will enjoy a different quality (which is mainly reflected in the bandwidth -the number of data transferred during a particular unit of time- and in the parallel services we are offered). Some examples of Internet connections are the BTL (Basic telephone Line), the ADSL (Asymmetric Digital Subscriber Line), the Optical Fiber Line (which offers the greatest bandwidth) or the Satellite.
In order to connect the Internet, we need to use specific hardware. This hardware is mainly:
-A modem: which turns the analogical information into a digital one and vice versa, in order to "translate" the information that our computer needs to send or receive into the signal that travels by the telephone lines.
-A router: which drives the packets of information it receives (remember Packet Switching) by the fastest ways to the final destination.
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