SSH
In plain terms
A protocol for securely logging into and controlling remote machines.
Going deeper
Secure Shell encrypts the connection to a remote server, letting you run commands and transfer files safely. Key-based authentication makes it both secure and convenient for administering systems.
Under the hood
Public-key auth is preferred over passwords; agent forwarding, tunneling, and config files streamline access, while key hygiene is a real operational risk.
Examples
ssh user@host, scp/sftp, key pairs, port forwarding, ~/.ssh/config, jump hosts.
Think of it like...
Like a secure, encrypted remote control for a computer across the world, where only your matching key fob works.