Authentication is the act of determining whether someone, or something, is what it declares itself to be. Authentication can provide robust access control to systems by checking a users identity against the credentials stored on that entities own database. Most users nowadays are very familiar with a simple User name and Password authentication mechanism, which is referred to as single factor authentication. This authentication mechanism can be further strengthened with the introduction of a second factor, or indeed multiple factors, commonly referred to as 2 Factor authentication and Multi-factor authentication respectively. Two factor authentication typically comprises of a Possession Factor ('Something you have' - like a key fob or smart phone) and a Knowledge factor ('Something you know' - like a password). Multi-factor authentication takes this a step further by further introducing some of the following factors; Inherence Factor ('Something you are' - a biometric modality such as fingerprint or iris scan), Location Factor ('Where you are' - usually determined via device GPS) and Time Factor ('When you are authenticating' - If I authenticate in the UK and then 1 hour later an authentication attempt comes in from Asia it's unlikely to be the same person and is rejected