This feature can optionally get turned on by going to Account ---> Two Step Authentication.
Click the on/off button to turn on/off. You will need to verify your phone and install the Authy app before being able to use this feature.
Two-step (or 2-factor) authentication adds an extra layer of security to your account. After you sign in with your username and password, you will get prompted to enter a code. If someone were able to get your password, they still wouldn't be able to get into your account without access to your phone.
After you add/verify your phone and install the Authy app, there are two ways to get a code:
1. We will send you one via a text message
2. Using a token generated in your Authy app
When prompted, enter your code to get logged into your account.