The card game Rummy is played by arranging cards into combinations called melds which are either sets (three or four cards of the same rank) or runs (three or more consecutive cards of the same suit). The typical goal is to be the first player to meld all of their cards except one, which is discarded to end the round. Here is a brief guide on how to play Rummy:

1. Players and Cards: Usually 2-4 players play with a single deck. Each player is dealt a certain number of cards (e.g., 10 cards for 2-4 players, fewer with more players).
2. Setup: The dealer deals each player their cards and places the remaining cards face down as the stock, with the top card placed face up to start the discard pile.
3. Turns: Players take turns in clockwise order. On your turn, you draw a card either from the stock or the discard pile. Then you may meld any valid runs or sets if possible.
4. Melding: A valid run is three or more consecutive cards of the same suit (e.g., 4-5-6 of hearts). A valid set is three or four cards of the same rank from different suits (e.g., three 7s from different suits).
5. Discarding: At the end of your turn, you discard one card face up onto the discard pile.
6. Ending the round: The round ends when a player has melded all their cards except one, which they discard last. That player wins the round.
7. Scoring: Players' remaining cards are scored as penalty points, usually with face cards worth 10 points, and other cards their face value.

Additional notes:

• Aces can be used as low (A-2-3) or high (Q-K-A) but not both in the same run.
• Players may also "lay off" cards on existing melds to reduce their hand.
• Jokers or wild cards may be used depending on the variant played.
• Different variants have specific rules for hand size and scoring.

This should give a solid overview of playing Rummy. For beginners, understanding melds (runs and sets), drawing and discarding cards every turn, and aiming to meld all cards first are the key points to start playing successfully.