SSH requires a public key and a private key and the authentication is considered asymmetric encryption. The client needs both the public and private key while the server just needs the public key at some point.

Connecting:

To connect, you just do: ssh -i "/path/to/key" user@server, where the server may be the domain name or the IP address. (Works on Linux+Windows)

ssh-copy-id

Of course, as per the protocol, the public key needs to be present on the host you’re connecting to. You can easily do this with ssh-copy-id user@remotehost. (Works on Linux+Windows)

ssh-keygen

For generating a key pair, you can do ssh-keygen -t ed25519. You can add -C "[email protected] to add some metadata as a comment. RSA is generally fine too. (Works on Linux+Windows).