There are two types of Stars you can earn in the game:
Gold Stars
Permanent and tied to each level
Up to 3 per level:
Completion Star – Win the level
Speed Star – Beat the timer
Streak Star – Fill the streak meter to 100%
Replay levels anytime to try for more
Red Stars
Reset weekly
Count toward your individual Red Star Leaderboard
Earned the same way as Gold Stars
Collecting Stars shows your progress, boosts your achievements, and gives you leaderboard glory!