A Basic Introduction to a Range of Internet Related Concepts and Terms

Addresses for computers

As most people know a network is a collection of computers or related devices which can intercommunicate across some transmission medium. A transmission medium can be set up with suitable 'wiring' or 'cabling' but it can also be set up using wireless, infra red, laser and other 'through the airways' technologies.

The computers may be connected locally within a room or within a building in which case we might talk about a local area network. They could also be connected globally as is the case of the Internet.

Some organisations have their computers linked together in groups of 'local' networks and the networks may linked to each other to form what is called an intranet. Networks and intranets tend to be 'secure' groupings of computers which can only be accessed by individuals with appropriate authorisation.

The Internet on the other hand provides a means of access for individuals to computers (and related information) which have been set up for public access. The Internet can also of course act as the 'highway' which provides individuals with access to secure systems or networks which have sophisticated password access facilities.

In order for computers (and their related programs) to interact with one another in a systematic and effective manner a number of 'systems' have been designed to define how data should be transmitted and received. A network protocol suite is a system of common rules which helps to define this process. TCP/IP (Transmission Control Protocol/Internet Protocol) is one such collection of rules designed to support network communications.

TCP/IP deals with issues such as the addressing of computers and how messages can be routed to these computers through complex network structures such as the Internet. There are also devices called routers, which you might read about which, exist solely to direct data to its correct destination. On any network every computer (and related devices) is usually allocated a unique number on that network by a network administrator (liken it to the number of a house on a street). Also any network connected to the Internet has a unique network ID associated with it - assigned to the network by the Internet Assigned Numbers Authority. Every individual computer on the Internet should thus have a unique address. This address or IP (Internet Protocol) number is thus used in the overall addressing structure of the Internet to identify individual computers.

139.133.196.66 is an example of an IP address used in The University of Aberdeen where: 66 is the address of one particular computer in one of the sub-networks of the University;

196 is a number which is associated with that particular sub-network - this number will be used by a router to direct data onto this network;

and 139.133 is a University of Aberdeen assigned number.

To access my personal web server it is possible to type http://terry.edu.abdn.ac.uk/~terry/ into your web browser (Internet Explorer or Netscape Navigator). It is however possible however to take another approach and use the IP address of this web server to obtain the same outcome. Try it out if you like. Type http://139.133.196.66/~terry/ rather than http://terry.edu.abdn.edu.ac.uk/~terry/.

The above example illustrates that IP addresses can be replaced by more meaningful names which are human-friendly translations of the IP addresses. This brings us on to the topic of domains, domain names, and the Domain Name System (DNS).