To reassure your real identity, two factor authentication method is used. Mostly all major online services for example email service providers (google, yahoo), online shopping portals, mobile phone recharging even on social media, two factor authentication method is used.
When you login into your email account, after feeding your email id password one text message is sent either on your mobile or on alternate email id. When you enter that code or text message called as OTP(one time password) only then you can successfully login into the account. This step re-confirms your ownership to that email account.
Suppose some hacker or cyber-criminal got access to your password and you are using two factor authentication, in that condition, the Cyber Criminal nether can access your email nor reset your email password.
In the next article I will explain how to setup two factor authentication for your email id.