Information theory is a branch of applied mathematics and computer science that focuses on the quantification, storage, and communication of data. It deals with the study of the fundamental limits on data compression, data transmission, and data storage. Key concepts in information theory include entropy, which measures the average amount of information produced by a random variable; mutual information, which measures the amount of information shared by two random variables; and channel capacity, which determines the maximum rate at which information can be reliably transmitted over a communication channel. Information theory has applications in various fields such as telecommunications, cryptography, data compression, and neuroscience. It has played a crucial role in the development of modern communication systems and technologies.