Hey, I'm Mickey Numbers, Professional Poker Player. Today I'm going to talk to you about checking.
First of all, checking can only occur post-flop. It cannot happen pre-flop because the blinds are in place, which are forced bets. You can only check when no one has bet first.
On the flop turner river, if you're first to act or your opponent checked to you, then you can also choose to check by saying "check" out loud or tapping the table.
Checking defers action to your opponents and after they act, you'll take your turn again. It's almost like saying "I pass" or "hold on, no bet yet".
If your opponents also choose to check on the flop or turn, then you get a free card.
On the river if your opponents choose to check after you do then you'll show down your hands which means the players will expose their cards and the best 5-card hand will win.
After checking, if someone bets, you'll then have the option to call the bet, raise the bet, or fold to bet, indicating that you've given up in the hand.
And that's the way checking works.