The document discusses the 2/1 bidding convention used in bridge. A 2/1 bid shows a hand with 4 cards in the suit bid at the 2-level in response to partner's 1-level opening bid. With competition, a 2-level response is invitational and a 3-level response replaces 2/1 as game-forcing. The 'principle of fast arrival' means faster bids indicate a more certain contract while slower auctions allow showing more hand details. Jacoby 2NT over a major opener shows support and at least 12 points when unsure about slam.