RIP and OSPF are interior routing protocols---that is, they're used for routing within an organization (or autonomous system in Internet lingo) and deal with technical routing issues (fastest link, most bandwidth, etc). BGP is for routing between organizations and deals with political issues than technical issues (we need to send all traffic here due to contracts, unless it goes down, then shift traffic over there; and refuse routing information from such-n-such organization because they don't have their act together).