What it is
Calibration distributes ratings to hit the quota: a capped share at the top, a capped share at the bottom. Managers trade employee stories against each other, and the written evidence, scope, and level mapping decide who lands in the capped share.
What to do about it: Write your own record before the meeting: dates, scope, and measurable outcomes. A rating that matches the calibration quota is argued with evidence, not with adjectives.
Plain-language description of US practice, not legal, tax, or financial advice. The paired guide carries the citations, dates, and thresholds; the state pages carry the local windows.