In telecommunication, the term acknowledgement is a response sent by a receiver to indicate successful receipt of a transmission. An example of an acknowledgement in this context is a protocol data unit, or element thereof, between peer entities, to indicate the status of data units that have been successfully received. More generally, an acknowledgement is a message from the addressee informing the originator that the originator's communication has been received and understood.

This article contains material from Federal Standard 1037C and adapted from the Department of Defense Dictionary of Military and Associated Terms.