Secure Shell or SSH is a client-server-based communication protocol that is used to connect securely from one machine to another. It uses a network port to create a connection session between the server that listens on the chosen port and the client which sends the SSH connection request on that port.
With this protocol, we can manage our servers and work on them remotely. For example, we can add/edit/delete the services running on the server using an SSH client like PuTTY or Terminal.