What are the main characteristics of passphrases?

What will be an ideal response?

Passphrases are generally used for private key protection. A public/private key system defines a mathematical relationship between the public key, that is known by all, and the private key, that is known only to the entity who created the key pair. The private key can only be unlocked by the passphrase created by the entity or user who generated the key pair. In general, passphrases are not the same as passwords. A user can set a password to be the whole passphrases, but this practice is not recommended. A passphrase is a longer version of a password that typically composed of multiple words in a sentence, and is, by definition, more secure. Because of this, a passphrase has more resistant against "dictionary attacks." All of the rules that apply to passwords apply to passphrases. A strong passphrase is relatively long and contains a combination of uppercase and lowercase alphanumeric and special or punctuation characters. An example of a strong passphrase is as follows: "I@#$%wor<>kAs()AnSoftware-++={}Architect."