Sometimes when you try to sign into a third-party website or service using your Facebook credentials, you will be sent a one-time password to confirm that the Facebook account belongs to you. It makes sense and it is also good security, although the only downside is that sometimes this makes the signup process a bit slow.
However Facebook has decided to change that as they announced changes that they will be making to Account Kit with Instant Verification. For those unfamiliar, Account Kit is a service used by developers to integrate Facebook-powered logins for their websites or services that relies on phone numbers and emails, which is why a one-time password is used to verify the user.
According to the changes Facebook is making, “Instant verification is the result of trying to streamline the login process and rely less on SMS for those signing in with their phone number. When a person enters his/her phone number into an app using Account Kit, via Android services, we attempt a match with the verified phone number listed on the person’s Facebook profile.”