OAuth 2.0 is an open standard for authorization that enables a third-party application to obtain limited access to an HTTP service. It is commonly used as a way for web users to log in to third-party websites using their Google, Facebook, or other accounts, without giving those sites their passwords.
The OAuth 2.0 protocol involves several different players: the resource owner, the resource server, the client, and the authorization server. The resource owner is the user who wants to grant access to their protected resources. The resource server is the server that hosts the protected resources, and the client is the application that wants to access those resources. The authorization server is the server that handles the authorization process, and issues access tokens to the client.
To obtain access to a protected resource, the client must first obtain an authorization grant from the resource owner. This is typically done by redirecting the user to the authorization server, where they can log in and grant the client access to their protected resources. Once the user has granted access, the authorization server issues an access token to the client, which the client can then use to access the protected resources on the resource server.
OAuth 2.0 provides several different authorization grant types, depending on the type of client and the type of authorization flow that is appropriate for the application. Some common grant types include the authorization code grant, which is used for server-side applications, and the implicit grant, which is used for client-side applications.
In summary, OAuth 2.0 is an open standard for authorization that enables a third-party application to obtain limited access to an HTTP service. It involves several different players, including the resource owner, the resource server, the client, and the authorization server. The client obtains an authorization grant from the resource owner and uses it to request an access token from the authorization server, which it can then use to access the protected resources on the resource server. OAuth 2.0 provides several different authorization grant types, depending on the type of client and the type of authorization flow.