Rules & Etiquette
Stop (jump) bids
Before making a jump bid, you must play your Stop card before making your bid, and leave it on the table for 10 seconds after making your bid. You should then put the Stop card back in the bidding box; the next player should not bid until you have removed the Stop card.
This gives all players time to think about what they will bid without it being obvious that they are hastily revising their plans! It also means that players have no excuse for making an insufficient bid (a bid that is lower than a previous one: eg, 2H - 2C)
A jump bid is one that is at a higher level than you need for that suit - eg, over a 1H bid, 2S is a jump because the player could have bid 1S.
Bidding at a level up from the previous bid is not automatically a jump bid - eg, over a 1S bid, if you want to bid hearts you have to go to the two-level, so you shouldn't play your Stop card if you bid 2H.
If you are not playing with a bidding box, say "Stop" before making your bid.
It is not illegal to play your Stop card and then make a bid that is not a jump bid (either because you have changed your mind, or because you thought you were making a jump bid), but you must never do so deliberately, and your partner must not draw any inferences from your use of the Stop card.