A set is three or more cards of the same rank, such as three 5s or four Aces. A run is three or more cards in sequence of the same suit, such as 5, 6, 7 of Hearts. Once a player has formed a set or run, they may lay it down on the table in front of them. Players can also add cards to sets or runs that are already on the table.

At the end of their turn, players must discard one card from their hand onto the discard pile. The game continues until one player has reached 500 points, at which point the game ends and the player with the most points is declared the winner.

Scoring:
Players earn points for every card they have laid down in sets or runs at the end of the game. Aces are worth 15 points, face cards are worth 10 points, and all other cards are worth their face value. Players also lose points for any cards remaining in their hand at the end of the game. Aces are worth 15 points, face cards are worth 10 points, and all other cards are worth their face value.

If a player has not laid down any cards by the time the game ends, they receive a penalty of 100 points.

Tips and Strategies:
1. Focus on forming sets and runs early in the game to increase your chances of getting rid of cards and avoiding penalty points.
2. Keep an eye on the discard pile and be ready to pick it up if it contains cards you need.
3. Try to pay attention to what cards your opponents are picking up and discarding to get a sense of what sets or runs they may be working on.
4. Don't be afraid to break up a run or set if it's not serving you well. You can always add cards to it later.
5. When you're close to reaching 500 points, be careful not to pick up too many cards from the discard pile as this can increase your chances of getting penalty points.

Overall, Rummy 500 is a fun and engaging card game that can be enjoyed by players of all ages. With its simple rules and strategic gameplay, it's no wonder the game has stood the test of time. So gather some friends or family members and give it a try!