Start at 501. Finish at exactly zero.
Each player starts a leg with 501 points remaining. You take turns throwing up to three darts. Add the points from your visit and subtract them from your previous total. There is no need to hit a particular ring to start in standard straight-in 501. A single 20, single 5 and treble 20 score 85, so your new remainder is 416.
The narrow outer ring doubles a number, and the narrow inner ring trebles it. In scoring notation, S means single, D means double and T means treble. Outer bull scores 25; the inner bull scores 50. A dart outside the scoring area or a bounce-out scores zero and is not thrown again. Record that miss too: it matters when you compare averages.
Understand double-out before you need it
Standard 501 ends on a double. With 40 remaining, D20 wins immediately, even if it is your first dart. With 50 remaining, the inner bull also wins because it counts as double 25. You do not throw the remaining darts after a valid finish. In the scorer, enter the finishing dart or confirm how many darts your checkout used.
A bust cancels the whole visit. It happens if you score more than your remainder, leave one, or reach zero without a double. Suppose you start on 32 and hit S20 followed by S12. You reached zero on a single, so you return to 32. A single 20 followed by D6 would have been a valid finish.
Choose a match you have time to finish
A leg is one race from 501 to zero. A best-of-five-legs match ends when someone wins three legs; you do not need to play all five. Sets group legs into larger matches. For a first session, one set and best of three legs is enough to learn the flow without committing your whole evening.
Use names everyone recognizes and agree on who starts. Keep the same finish rule throughout the match. If someone mistypes a score, undo the last visit before throwing again. The scoring mistakes guide explains what to check. DartsRound saves the current game on your device, so an accidental refresh does not mean starting over.