For a while, it seemed like two-factor authentication was going to stump hackers for years to come. Its strength lies in giving you two distinct factors of authentication, mainly what you know and what you own. That is why when you enter a password (something you know) on a certain website, you're also asked to enter a code sent to your phone, tablet, or computer (something you own) in the form of a text message or push notification. It can also be something you are, like a fingerprint or facial scan. Once you log into a website using 2FA, you begin what's known as an authenticated session.