The method of authentication everyone is familiar with is the username and password. While the username often reflect the individual's name, authentication is based on a database (logical) that contains this information and an encrypted password. End users and administrators should use common sense when selected a password for an operating system or application. Passwords need to be complex and policies need to be set in the group policy editor.
Passwords should contain alphanumeric characters and symbols. Spaces are highly accepted in order to create passphrases. As you know, passwords should not be written down or shared. Even if the scenario you are in becomes inconvienent and you 'want' to give your password.