Code repository GitHub offers two-factor authentication to beef up security around its users’ accounts. Users have to enter their username and password, and a secret code in the second step, to complete the sign in. If a hacker manages to steal a user’s credentials through phishing or trojans, cannot do anything, as they do need a second key to enter. Users can either choose to receive the second authentication factor via a text message or can use dedicated authentication mobile app i.e. Google Authenticator.
Source: https://thehackernews.com/2013/09/code-repository-github-offers-two.html