An improvement cycle based on the scientific method: a change in a process is proposed, the change is implemented, the results are measured and appropriate action is taken. The cycle is also called the Deming cycle or the Deming wheel, after W. Edwards Deming, who introduced the concept in Japan in the 1950s.
The PDCA cycle consists of four stages:
Plan: identify the objectives for a process and the changes needed to achieve those objectives.
Do: implement the changes.
Check: evaluate results in terms of performance.
Act: standardize and stabilize the change or restart the cycle, depending on the results.
Toyota often uses PDCA, but uses slightly different terminology (grasp the situation or go see):