Most of us have used Facebook as a simple way to log into accounts. Today, Facebook's making it even easier by allowing you to login to websites with just your phone number. You don't even need to have a Facebook account. The feature is part of Facebook's new Account Kit program. A developer can use Account Kit to add support to their apps or websites for phone number login.
Logging in with your phone skips the password altogether. When you login with Account Kit, you'll enter your phone number. Then, Facebook will text you a code that you can use to confirm that you're the one logging in. It's a bit like skipping straight to the second step in two-factor authentication. It also means you won't be able to login to any account where you used Account Kit unless you have your phone with you, which may be a good thing.