You can give me access to your SSH server by appending my public SSH key to its list of authorized users. This is also known as trusted SSH or passwordless SSH.
The Secure Shell (SSH) is a protocol for secure remote login and other secure network services over an insecure network, such as the internet. The SSH transport layer is a secure, low level transport protocol, that provides encryption, cryptographic host authentication and integrity protection. Read more about SSH in RFC 4253.