The term biometrics refers to technologies that measure and analyse human physiological or behavioral characteristics for authentication or identification purposes. Some of the most widely used characteristics or biometric factors are fingerprints, irises, voice patterns and the spatial geometry of the face.
To start with, let us explain why biometrics are needed more than ever. Physical access control, say to a building, is generally based on locks and keys, on badge readers or on few-digit pincodes which are easily lost or stolen by malicious individuals. Because for access control based on keys or badges the authentication factor is something you have, there is no real guarantee that the person entering your building is the individual that was granted access in the first place.
The same accounts for access to computerized systems, access control there is mostly based on passwords or pincodes thus the authentication factor is something you know. Unfortunately end users have to remember such an amount of passwords and pincodes that they no longer apply good password practices. End users tend to write passwords down, to keep new passwords as simple as possible and to use always the same password.
With biometrics the access control factor is something you are, a measureable physiological or behavioral characteristic, which is often more difficult to fake, steal or immitate than a password or a key. Users don't have to remember it and they cannot by accident leave it at home. This physiological or behavioral characteristic is referred to as a biometric factor, it can be your fingerprints or the way you use your voice.