2-Tier Authentication System, 2-factor authentication (2FA), is a tool for better account protection by adding a request to enter a confirmation code before logging in.

Operating principle:

This tool can help us to get rid of password lookups from people around us by the simple principle: Authentication code changes over time, or need a device has been "trusted" before you can sign in, even if they know your password.
Double layer security typically requires a secondary authentication element, possibly a sent message authentication code, an authentication code provided via an authorized application, an authentication code sent to other devices have been authenticated. Therefore, it takes a bit more time to turn on this option. However, according to me, a little time spent it completely worthy of what this tool bring yourself.

Happy to help if you want to know more. Thanks.