3-way Handshake: A three-step process used in network communications to establish a connection between a client and a server in TCP/IP protocol. The handshake begins when the client sends a SYN (synchronize) packet to the server to request a connection. The server then responds with a SYN-ACK (synchronize-acknowledge) packet to acknowledge the request. Finally, the client sends an ACK (acknowledge) packet back to the server to confirm. Once this process is completed, the TCP connection is established, allowing for data transmission to take place. This handshake is essential for initiating a reliable session between two devices over a network.

99.999 Uptime: The high availability of a system or service, quantified as being operational 99.999% of the time, often referred to as "five nines". This equates to a downtime of approximately 5 minutes and 15 seconds per year, thus indicating a system with highly reliable and uninterrupted service. High availability is crucial for systems where even minimal downtime can lead to significant operational or financial impact.