The rules, at a glance
Aim for the lowest score
Four players each receive 13 cards. Each heart you take adds 1 penalty point; the queen of spades adds 13. Other cards add no points.
Pass three cards
Choose three cards before looking at the cards coming to you. Pass left on the first hand, right on the second, across on the third, and keep your cards on the fourth. Repeat that pattern. Passing choices depend on your whole hand.
Follow the suit that was led
After passing, whoever holds the two of clubs plays it first. Play goes clockwise. If you have a card in the suit that was led, you must play that suit. The highest card of that suit wins the four-card trick and leads the next one. Aces are high.
Discard when you cannot follow suit
If you have no cards in the led suit, you can play another suit. This can let you give a heart or the queen of spades to the trick's winner. On the first trick, this site's rules require a non-penalty discard if you have one.
Breaking hearts
The first heart discarded on another suit breaks hearts. Players may then lead hearts, but must still follow the led suit when possible. On this site, the queen of spades does not break hearts. A player holding only hearts may lead one before hearts are broken.
Count the score
An ordinary hand has 26 penalty points in total. Scores carry over between hands. At the default setting, the game ends when someone reaches 100 or more; the lowest total wins. You can choose another target in the game settings.
Shooting the moon
If one player takes all 13 hearts and the queen of spades in the same hand, that player scores zero and each opponent receives 26 points under this site's standard scoring. It is a risky strategy. One missing heart means the moon attempt fails.
These examples follow OnlineCardGames.io's Classic Hearts rules. Other tables and variants may use different house rules.