In Diablo 4, items are categorized by rarity and power, often indicated by star ratings. Normal items have no stars, Magic items have 1 star, Rare items have 2 stars, Legendary items have 3 stars, and Unique items have 4 stars. The star rating usually reflects the item's rarity and the number of affixes or special properties it has. Higher-star items typically offer better stats and unique effects.