This document is a summary of the information contained in Chapter 5 of Projective Geometry by Albrecht Beutelspacher and Ute Rosenbaum. When data is stored or transmitted it is possible that errors will occur. The main goal of Coding Theory is to detect and, if possible, correct those errors. Information stored on a disc for your PC may have some back-up and error correction capability built in, but you may irretrievably lose data in some circumstances. Information being transmitted from a satellite taking close-up pictures of Saturn may be compromised in many ways, and it probably makes good economic sense to plan ahead for these errors rather than try to launch another satellite if a picture comes out fuzzy.
Any model of communication includes a sender, a receiver, and information.
There are always barriers to communication, and coding theory is specifically focused on physical barriers. When transmitting data, the basic medium is an electronic signal which has two different characteristic states. These are interpretted as 1's and 0's and form the code from which any message is built. Your digital phone or camera, your photo e-mail, your term paper, and any other signal sent through a wire or the air in the 21st century is most likely, on a very basic level, a long string of 1's and 0's. Any incorrect character in the string can cause an error, from a typographic mistake to the termination of a program.