In computing, an ACK (also known as an acknowledgment code) is a signal passed between communicating processes or computers to signify acknowledgement, or receipt of response, as part of a communications protocol. For instance, ACK packets are used in the Transmission Control Protocol to acknowledge the receipt of SYN packets when establishing a connection, data packets while a connection is being used, and FIN packets when terminating a connection. Memory (Random Access Memory) Look up computing in Wiktionary, the free dictionary. ... A signal is a limited form of inter-process communication used in Unix, Unix-like, and other POSIX-compliant operating systems. ... In computing, a process is an instance of a computer program that is being executed. ... A BlueGene supercomputer cabinet. ... For other senses of this word, see protocol. ... In information technology, a packet is a formatted block of information carried by a computer network. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite, often simply referred to as TCP/IP. Using TCP, applications on networked hosts can create connections to one another, over which they can exchange streams of data using Stream Sockets. ...