Definition of hole card
Hole cards are the cards in the hole. What is meant by hole cards in Hold'em, for example, are the two hole cards that each player receives before the flop. The 7 total cards a poker player can use if the hand goes to the river are the flop (3), turn (1), river (1) and hole card (2). These cards must be hidden until the showdown. If all players have folded and you win the pot by default, you do not have to show your hole cards.
Showing your hole cards in a bluff?
As we said before, if all the players fold before us, we will win the pot by default. At this point, we can throw away our cards without showing them. But if for example we call a big bluff that works, should we show our hole cards or not? Most of the time not. Poker is a game of incomplete information and when you show your cards to your opponents, they get free information about you. If you want to show your hole cards in a hand, make sure you have a good reason for doing so.