mechanism: knowledge (something the user and only the user knows), possession (something the user and only the user has), and inherence (something the user and only the user is).
What is 2FA?
2FA or two-factor authentication is a way to double the security to your accounts. 2FA can be used for many types of services. Surprised or not two-factor authentication has been used for years. 2FA is security measurement that requires you to have two ways of authentication, one that you know and one that you have. For example your credit card. When you go to pay you swipe your card (something you have ) and then enter your pin (something you know ). In our case is a little bit more complicated.
Why to use second factor for authentication?
By using second factor authentication you make your account a less attractive target for hackers. For example if your house has a security system it makes it less attractive to thieves. And if you have a large, loud dog in your house and a security system, the odds of a burglary inside your house are very low. The thieves wont want to bother with a house with alarm and big dog. They will just find another house without them. The same is with your accounts. If a hacker wants to get your account they have to know both your password and the one time unique key that you are using. So they wont bother and will find an easier target.