A value stream is all the actions (both value added and non-value added) currently required to bring a product through the main flows essential to every product:
the production flow from raw material into the arms of the customer
the design flow from concept to launch
Taking a value stream perspective means working on the big picture, not just individual processes, and improving the whole, not just optimizing the parts.

Value Stream Mapping is a pencil and paper tool that helps you to see and understand the flow of material and information as a product makes its way through the value stream. The meaning is simple: Follow a product's production path from customer to supplier, and carefully draw a visual representation of every process in the material and information flow. Then ask a set of key questions and draw a "future state" map of how value should flow.

Within the production flow, the movement of material through the factory is the flow that usually comes to mind. But there is another flow - of information - that tells each process what to make or do next. You must map both of these flows.

Value Stream Mapping can be a communication tool, a business planning tool, and a tool to manage your change process. The first step is drawing the current state, which is done by gathering information on the shop floor. This provides the information needed to map a future state. The final step is to prepare and begin actively using an implementation plan that describes, on one page, how you plan to achieve the future state.

More and more organizations with successful shop-floor lean efforts are also applying Value Stream Mapping methods and lean principles to administrative areas. Value Stream Mapping provides a simple, yet thorough methodology that relies on relevant data analysis and display. It links reporting requirements, metrics, people, and lean tools to sustain improvement and promote process learning. It gives managers and employees the same tool and language to communicate.