Coding theory is a relatively new science that deals with the problem of transmission of information through the channel with noise and interference. Information is coded in a way that enables us to detect and correct mistakes made during transmission. In the first chapter, we will describe Shannon’s general communication system, while the second chapter is going to deal with the definitions of Hamming’s distance, block code and minimum code distance. We will demonstrate three propositions that will give us an analysis of the best possible results while in search for good codes. In the third chapter, we will deal with linear codes. We will learn some important linear code properties, describe it using the generator matrix and parity-check matrix. We will also define the equivalence of general and linear codes, define the orthogonal code, along with its properties, and then link the C code and its orthogonal code. At the very end we will show that we can construct new codes from the already existing ones, describe the methods that can be used to achieve aforementioned and link codes and other final structures.