Benefits realisation starts before delivery. Each initiative names the benefits it will produce, how they will be measured, and who owns them. Delivery is then steered against those benefits, not just against milestones and budget.
The discipline continues after go-live. Many benefits accrue only when new ways of working are adopted and held. Benefits realisation tracks the gap between projected and actual benefits and prompts action to close it, keeping investment cases honest.
For enterprises and consulting leaders, it is the mechanism that connects spend to result. It answers the question boards keep asking: what did we actually get for the investment.