A stopper is a protected honor held by the offense in a notrump contract. Stoppers are essential, particularly in shorter suits when the declarer must give up the lead while establishing another suit, by preventing the defense from running their long suit.

All the following suits contain one stopper:

  • A
  • KQ
  • QJT
  • KJxx (If the A and Q are under it, both the K and the J can stop the suit, however, it both the A and Q are over it, the K and the J are useless)

All the following suits contain two stoppers:

  • AK
  • KQJ
  • QJT9

The following suit contains a half stopper only:

  • Kxx (The K can stop the suit only when the A is under it)

The following suit contains one and a half stoppers:

  • AQx (If the K is under the suit, there are two stoppers; if the K is over it, there is only one)

The following suits contains no stoppers at all:

  • K (an unprotected honour)
  • QJ (unprotected honours)
  • xxx (small cards in short suits)