In cybersecurity, multi-factor authentication is a login method where users have to enter an extra input to prove they’re the user. This is usually time-sensitive codes generated by an authenticator device (either an app or physical hardware), or through app authentication (think Google, Adobe).
I use Authy as my 2FA app — currently considering switching to a better-regarded open source alternative. I used to use Google Authenticator but they didn’t have cloud back-ups at the time (which can be problematic if the device fails).