In computer networking, telecommunications, and computer buses, an acknowledgement (ACK) is a signal that is passed between communicating processes, computers, or devices to signify acknowledgment, or receipt of message, as part of a communications protocol). The ACK signal is sent by a receiving station to the sending station after the receipt of a recognizable block of data of specific and expected size. The ACK communications code is usually an American Standard Code for Information Interchange character (0000110 or 6) that is reserved and designated for the purpose of signaling communication between the destination station and the sending station.
Apart from its usage in computer networking, "ack" is also a slang term that is used to express mild alarm, dismay, frustration, or surprise.
