Google Authenticator is one of the most valuable tools we can use when dealing with online accounts in cryptocurrency.
The Google Authenticator implements what is called two factor authentication (2FA for short). It uses a time based password algorithm. This means that both your Google Authenticator app and the service you are logging into have agreed to a specific time code, that is private and allows them to synchronise with each other to confirm passcodes. To use Google Authenticator, you must download it on to your device and set it up. You can add multiple accounts with one app. So you could have a wallet account and an exchange account.
We will assume you are using it for an exchange. Once setup on your exchange account you will be prompted to enter 2FA after you log in with your normal password. If you cannot input the 6 digit code that Google Authenticator produces, you cannot access the account. This makes it very hard for hackers to access your account, as they must have your Google Authenticator code in addition to your password to log in. Due to Google Authenticator being time based, every 30 seconds a new 6 digit password is produced, 24 hours a day.
While this is great for preventing unauthorised access it comes at the cost of convenience. Always remember to safely store your Google Authenticator back up code, or if you lose your phone (or other device you have your Google Authenticator on) then you will not be able to access your account/s. Remember your 2FA is only as secure as where you store your back up code. Treat it like any other private key or PIN.