If you don t want to go higher, you stop, usually by saying Pass. When you and your partner both pass, you are agreeing that you have climbed high enough. The rung at which you and pard stop on this bidding ladder becomes the final contract. Remember that there are 13 tricks in a deal. The first six are book.
Book is a prerequisite to start the bidding.
Seven more tricks remain. So, you can bid for as few as one to as many as seven tricks above book. Each trick above book for which we bid is considered a Level of bidding. So, we can bid at the one level, or the seven level, or any level in between. There is another rule of the bidding ladder.