The flow of information about customer requirements upstream to where that information is needed to drive each operation.

In mass production companies, information flow usually takes parallel forms: forecasts flowing back from company to company and from plant to plant, schedules flowing back from company to company and from plant to plant, delivery orders by the day (or by the week or by the hour) in which each facility is told
what is to be produced on the next delivery, and accelerated information by which forecasts, schedules and delivery orders are withdrawn to adjust the production system to changing conditions. 

Lean companies are trying to simplify their information flows by creating a single production planning point and setting up pull loops for information. These run upstream in the value stream, that is, always to the previous production point and from that point to the production point before it - all the way to the first production point. 

The illustrations show the different routes for information flows in mass production compared with the simpler flows in Lean production. Lean producers, by the way, still provide forecasts because companies and facilities further away from the customer need advance information to plan capacity, schedule their staff, calculate branch times, account for seasonal variations, introduce new models and so on. However, the daily flow of production information can be compressed into simple pull loops. 

An example of a current state information flow in mass production:

An example of a future state information flow at Lean production: