Trapping your opponent means that you check a strong hand in order to induce your opponent to bluff or bet a worse hand.
Sometimes trapping your opponent is the best way to get all of his chips.
WHEN TO TRAP
When you have the nuts: When you have an extremely strong hand, sometimes you don’t want to chase your opponent away with a strong bet. You may also want to give your opponent a chance to catch a stronger hand on a later street so you can get paid off.
On dry boards: Your opponent will miss the flop often on dry boards, making them better to trap on when you have a stronger hand, in hopes that your opponent will bluff you or catch a good card on the turn.
Against an aggressive opponent: Aggressive opponents love to bet if they sense weakness, so trap aggressive players more often.
When you have a tight image: When you are perceived as a tight player, you may want to consider trapping your opponents by checking, as a strong bet may show that you have a strong hand if you’ve been tight.
WHEN NOT TO TRAP
When you a strong hand that is vulnerable: If you’re hand is strong, but not the absolute nuts, it is usually just to bet for value, protection, as well as being able to narrow down your opponent’s hand range easier.
On wet boards: When there are a lot of draws on board, it is best to play your strong hands fast by betting and not trapping.
Against tight opponents: Tight opponents will not bluff as often, so it is best to just bet for value against them to try to get paid in full.
When you have a loose image: If you are percieved as a loose player, then you don’t want to trap as often. This is because people will call you with worse hands than normal because you are looser than a normal player. They also may be scared to bluff against a loose player.