OAuth (Open Authorisation) is a protocol that lets a user grant a third party limited access to their data on another service without sharing their password. When you allow an app to read your contacts from a social network or post on your behalf it receives an access token that defines exactly what it can do and for how long. These tokens can be restricted in scope and revoked at any time. By separating identity verification from permission granting, OAuth protects user credentials and gives precise control over what data applications may access.
