OAuth/Open authorization:
It is an way by which users can grant access to their information on the other website without sharing the password. OAuth is an standard which governs that how the application is going to fetch the information from the other website. There are few components which is being used in this these are:-
Authorization Server: This maybe an application such as Facebook, Google which originally have your information..
Client Application/Client Resource: Any application which want to fetch your information from the website which originally have it. (Fetching the information from the authorization server).
So let suppose while applying for a job on any company their website asks you to login or to fetch your information from the Google or Facebook now instead of creating the account on the website you choose to fetch the information from the facebook. You click on Login with Facebook button, the application opens up a popup windows and asks for your facebook credentials as soon as you provide the facebook credentials application asks you to authorize the job company so that it can fetch the information from the website. As soon as you click on the authorize facebook provides a secret access token to the job company which can use this to fetch your information from the Facebook.
