Adoption is the extent to which people actually use something as intended after it is delivered. It is the behavioral half of change: not whether a system, process, or tool has been rolled out, but whether the people it was built for have genuinely taken it up and changed how they work.
Adoption is distinct from deployment, and the distinction is where benefits are won or lost. Reporting deployment as "done" assumes a benefit that only adoption delivers: with no adoption, there is no outcome and therefore no benefit, no matter how complete the rollout. Change management is the discipline aimed specifically at securing adoption.
