why do we need both access token and request token?

[leec651]

I don’t understand why do we need both access token and request token. Wouldn’t having only access token be sufficient enough?

For example, in the Oauth workflow I read from hueniverse:http://hueniverse.com/oauth/guide/workflow/
beppa(client) can just redirects Jane(resource owner) to faji(server) on its behalf and get the access token after Jane logs in to faji. Can someone please tell me why? Thanks!!

[leec651]

I'm not sure if this is correct. I googled it a bit more, and it sounds like request token is used by the client to identify itself to the server. Is that right?