Almost everyone agrees that passwords are an outdated method of authenticating users - but it's still the most common authentication method, by far. That's at least in part because other methods have their drawbacks. Two factor authentication using smart cards or tokens provides better security, but require that you keep up with the physical device and have it with you when needed. Traditional biometric security such as fingerprinting or retina/iris scanning seems awfully intrusive to many people.
We've generally authenticated users via something you know (passwords/PINs), something you have (smart card or token) or something you are (biological traits such as fingerprints). A fourth means of authenticating involves something you do. The latest entry in that field to gain supporters is keystroke authentication - pattern analysis that examines how you type. Researchers at Iowa State University even think it could replace passwords. Read more and see the video here: