submitted by Bumhan Yu
Over the web, there have emerged a variety of applications and services (client) that need access to data resources from a user (resource owner) on another service provider (server)--e.g. printing app to access photos on Flickr site--which can cause security/privacy concerns should users provide their full passwords and complete access to private resources. For such uses, OAuth provides a method for users to grand third-party access to their resources without sharing their passwords. Unlike traditional client-server authentication model, where client uses its credentials to access the resources on the server, OAuth model has a third role the resource owner.
As shown in the diagram above, user (resource owner) authorized permission for client to access resources. This auth
