Oauth is an open standard for authorization that allows secure authorization from web, mobile and desktop applications. This standard allows a third-party application to gain access to a HTTP service, i.e. it enables users to share their resources from one website with another website without having to give out their credentials (usually username and password). Oauth is implemented on websites that support web and mobile applications or have their own APIs. Many popular websites, such as Google, Facebook and Twitter, use Oauth for third-party application authorization.