Lean is way to determine value sought by customers, provide value through an end to end process, value stream, by engaging everyone touching the value stream to minimize waste, variations and overburden throughout the value stream.
The core idea is to maximize customer value while minimizing waste.
Simply, lean means creating more value for customers with fewer resources.
A lean organization understands customer value and focuses its key processes to continuously increase it. The ultimate goal is to provide perfect value to the customer through a perfect value creation process that has zero waste.
Eliminating waste along entire value streams, instead of at isolated points, creates processes that need less human effort, less space, less capital, and less time to make products and services at far less costs and with much fewer defects, compared with traditional business systems. Companies are able to respond to changing customer desires with high variety, high quality, low cost, and with very fast throughput times. Also, information management becomes much simpler and more accurate.