the prepared club opening bid in bridge
Clubs are the lowest ranking suit in bridge and are easy to outbid with the other suits. On top of that, you need to make eleven tricks to make a game in clubs and it is therefore no surprise that, over the years, some bids in the club suit have been adapted for artificial bidding. The lowest bid of all is one club and the artificial use of that to open the bidding has become very popular. It works like this:
The person opening the bidding has a strong hand, (usually 15 to 16 points or more but less than 20). The hand does NOT contain a five card major suit and the bidder would love to bid one no trump but can't because his/her partner would think it was showing 12 to 14 points. (This only applies if the pair use weak no trumps opening bids).
S/he opens the bidding with one club, the prepared club bid, which shows a strong hand and no five card major suit. The responder replies one diamond if they have less than six points and one no trump if they have six to nine points but gives a positive response in their best suit otherwise. Bidding then continues naturally.
It is important to note that the opening bidder may have NO clubs in their hand or they may have many. For this reason it is imperative that their partner replies no matter what value they have.
If the player next to the opener bids, the opener's partner may pass with a very weak hand. It goes without saying that both partners must know and understand that they are playing this system for obvious reasons.