When you set up SSH, you'll generate an SSH key and add it to the ssh-agent and then add the key to your GitHub AE account. Adding the SSH key to the ssh-agent ensures that your SSH key has an extra layer of security through the use of a passphrase. For more information, see "Working with SSH key passphrases."
We recommend that you regularly review your SSH keys list and revoke any that are invalid or have been compromised.
If you're a member of an organization that provides SSH certificates, you can use your certificate to access that organization's repositories without adding the certificate to your GitHub AE account. For more information, see "About SSH certificate authorities."