The small mark in the bottom left of a Pokémon card that shows its rarity. In the Scarlet & Violet era it runs from a circle for Common up to three golden stars for Hyper Rare.
For new players
Star colour matters: black double stars are Double Rare, white or silver double stars Ultra Rare, golden double stars Special Illustration Rare, and a single golden star Illustration Rare. Older cards do not always follow the same system.