Encyclopedia Britannica's says that "the chief concern of information theory is to discover mathematical laws governing systems designed to communicate or manipulate information. It sets up quantitative measures of information and of the capacity of various systems to transmit, store, and otherwise process information. Some of the problems treated are related to finding the best methods of using various available communication systems and the best methods for separating the wanted information, or signal, from the extraneous information, or noise". The study of information theory is also concerned with the definition of notion of information in a general sense and with a unified information theory that is supposed to contain all the statements of existing information theories.