In computers, encoding is the process of putting a sequence of characters (letters, numbers, punctuation, and certain symbols) into a specialized format for efficient transmission or storage. Encoding is nothing but a character recognization system. Decoding is the opposite process, Thre are four types of encoding system exist in the world. the conversion of an encoded format back into the original sequence of characters. Encoding involves the use of a code to change original data into a form that can be used by an external process.