A word uttered my two English-speaking humans when they first encounter each other. It is used for calibrating
the speech-processing wetware to compensate for accent, pitch, volume, nasal congestion etc. It roughly translates
as Can you hear me? Are you willing to talk to me? By extension, the first exchange of messages in a
protocol. The term by extension refers to the first messages exchanged in a computer communication protocol to
establish that the identity of the other end and its ability to communicate in the expected protocol.