For communication to occur, there must be somebody at the other end of the channel. This person or persons can be called the receiver. To put it in Shannon’s terms, information transmitters and receivers must be similar systems. If they are not, communication cannot occur.
(Actually Shannon used the term destination, reserving the term receiver for what we have called decoder. However, I think the terminology I have been using is more common in the broader understanding of ‘communication theory’ as distinct from Shannon’s information theory.)