Business process improvement (BPI) is a systematic approach to help an organization optimize its underlying processes to achieve more efficient results. The methodology was first documented in H. James Harrington’s 1991 book Business Process Improvement.[1] It is the methodology that both Process Redesign and Business Process Reengineering are based upon. BPI has been responsible for reducing cost and cycle time by as much as 90% while improving quality by over 60%.
Process improvement is an aspect of organizational development (OD) in which a series of actions are taken by a process owner to identify, analyze and improve existing business processes within an organization to meet new goals and objectives,[2] such as increasing profits and performance,[2] reducing costs[2] and accelerating schedules.[citation needed] These actions often follow a specific methodology or strategy to encourage and ultimately create successful results.[2] Process improvement may include the restructuring of company training programs to increase their effectiveness.[2]
Process improvement is also a method to introduce process changes to improve the quality of a product or service, to better match customer and consumer needs.[2]

Source: http://en.wikipedia.org/wiki/Business_process_improvement