In networking, a handshake is a series of automatic messages exchanged between two devices to establish, configure, and verify a communication link before actual data transfer begins, ensuring both parties agree on protocols, parameters (like speed), and readiness, similar to a real-world greeting before a conversation. The most common example is the TCP Three-Way Handshake (SYN, SYN-ACK, ACK) used for reliable connections or the TLS Handshake (SSL/TLS) for secure HTTPS, which negotiates encryption keys.