Definition: Exposure control is a technique for reducing the risk of testing in production by limiting how many users can be affected by new code. The new code is first exposed to a small share of users or traffic, and that share is increased as confidence grows.
So what? If new code has a serious problem, exposure control keeps the damage small and buys time to detect and fix it. It makes testing in production a managed risk rather than a gamble.
Examples: Triggering a new back-end feature from only 1% of page views, then slowly ramping up. Rolling a change out to internal staff, then a small group of external users, then everyone.
