handshake
n. countablen. a way of greeting someone by grabbing and moving their hand up and down. In computing, it also means the way two machines agree on how to talk to each other.
n. a formal greeting or agreement involving the grasping and shaking of hands; in computing, the automated process of establishing communication protocols between two systems.
They sealed the deal with a firm handshake.
The server and the client perform a TLS handshake to establish a secure connection before exchanging data.
While the traditional handshake remains a staple of international diplomacy, the digital handshake between their respective networks proved far more difficult to coordinate due to legacy software issues.
From hand + shake. See the appendix for the history of the gesture itself.
In its computing sense, often used as a modifier ('handshake protocol') or as a singular process.