2 factor authentication

Two-factor authentication is a neat technique for adding extra security by requiring two different types of verification. So, rather than asking you to provide two passwords—both things you could remember or find written down—if you are asked to provide a password and a code you could only have if you had a particular device, security is greatly enhanced.

The usual factors involved include asking for two from:

1. something you Know
2. something you Are
3. something you Have

Hence the convenience of photo ID where you have to provide the ID and also look like the photo. Or provide a ticket and a code, or a chip and pin…

Also see: choose passwords that make you happy, and 8 character passwords