It replaced OAuth 1.0 in 2012 and is now the de facto industry standard for online authorization. OAuth 2.0 provides consented access and restricts actions of what the client app can perform on resources on behalf of the user, without ever sharing the user's credentials.
OAuth (Open Authorization) is an open standard protocol for authorization of an application for using user information, in general, it allows a third party application access to user related info like name, DOB, email or other required data from an application like Facebook, Google etc. without giving the third party app the user password.