The objective of lean is to create the most value for the customer while consuming the least amount of resources to design, build, and sustain the product. Companies will gain improvements from lean when they redesign their value streams by applying the following principles:

• Specify value from the standpoint of the customer
• Identify the value stream for each product or service-line family
• Make value flow toward the customer
• Produced based on the pull of the customer, and
• Strive continually to approach perfection.

Full article: Lean Tools and Methods: An overview