The passphrase requires a few more keystrokes than its predecessor, the password. This simple fact makes it more secure, but also easier to remember when stringing together random words. The passphrase eliminates the need for special characters and numbers, making it more convenient to type into mobile devices.
Still not sure? Maybe this infographic will help.

Note: Students, faculty and staff are not allowed to share their password with anyone. Doing so is impermissible under the University’s Computing Resources Acceptable Use Guidelines.