What’s a passphrase? It’s a phrase or sentence that you use as a password. Phrases tend to be easier to remember than ordinary passwords, and they are much more difficult to crack.

This month’s Ouch! newsletter (PDF) provides a useful overview of passphrases and their use. Note that while passphrases can be very strong, you should still make sure to use a different one for each site or service. And of course you should use a good, offline password manager like Bruce Schneier’s Password Safe to keep track of them.