The probability that a specific item appears in a single attempt (e.g., chest, kill, or roll). Expressed as a percentage or 1-in-N.
If a boss has a 5% drop rate for an item, the chance to get at least one in 20 attempts is 1 − (1 − 0.05)^20.
Drop rates may change across seasons or patches. Always confirm the current table for your activity.