Passphrase

A passphrase is a sequence of words or other text used to control access to a computer system, program or data. A passphrase is similar to a password in usage, but is generally longer for added security. Passphrases are often used to control both access to, and operation of, cryptographic programs and systems. Passphrases are particularly applicable to systems that use the passphrase as an encryption key. The origin of the term is by analogy with “password”.
from Wikipedia

The best passwords are not one or two words, but are phrases that are easy for you to remember and hard for anyone else to guess. They can also be completely random symbols. A password like of random characters is basically impossible to guess. But also impossible to remember.