Weighted loot table
Also said as Loot table, Drop table, Drop rates
A list of what can drop, each with a weight. Add up the weights, roll a number in that range, and see whose slice it lands in. A weight of 1 in a table totalling 100 is a 1% chance.
It puts an item's rarity in one number a designer can change without touching code. Most of the mistakes come from forgetting that adding a new entry shrinks the share of everything else.
Say it
“Set the boss loot table to weights 70 common, 25 rare, 4 epic and 1 legendary. Roll it 100,000 times in a test and check the shares before we ship.”
Where you’ve seen it
Minecraft stores its chest and mob drops as loot tables in plain data files: pools of entries, each with a weight, so anyone can read and change them in a data pack.
Not to be confused with rarity
Rarity is what the player is told: a label and a colour. The weight is the real number behind it. The two drift apart if nobody is checking.