A Mathematical Theory of Communication is an article by mathematician Claude E. Shannon published in Bell System Technical Journal in 1948. It was renamed The Mathematical Theory of Communication in the 1949 book of the same name, a small but significant title change after realizing the generality of this work.

Shannon's article laid out the basic elements of communication:
* An information source that produces a message
* A transmitter that operates on the message to create a signal which can be sent through a channel
* A channel, which is the medium over which the signal, carrying the information that composes the message, is sent
* A receiver, which transforms the signal back into the message intended for delivery
* A destination, which can be a person or a machine, for whom or which the message is intended
* It also developed the concepts of information entropy and redundancy, and introduced the term bit (which Shannon credited to John Tukey) as a unit of information. It was also in this paper that the Shannon–Fano coding technique was proposed – a technique developed in conjunction with Robert Fano.