A large modern distribution center might extend over 600,000 square feet (60,000 square meters), contain( 600,000 square meters), contain a hundred thousand SKUs, and have hundreds of people working to gather and consolidate thousands of customer orders in time to meet daily ship- ping schedules.

How can such coordination be achieved?
    A Warehouse Management System (WMS) is a complex software package that helps manage
inventory, storage locations, and the workforce, to ensure that customer orders are picked quickly, packed, and shipped. A typical WMS knows about every item in the warehouse, its physical dimensions, how it is packed by the vendor, all the storage locations in the warehouse, and their addresses and physical dimensions. With this knowledge, the WMS orchestrates the flow of people, machines, and product.
    The WMS receives customer orders and transforms them to pick lists organized for easy retrieval: In customer orders items appear in arbitrary sequence, just like the grocery shopping list one might casually prepare during the week. When it is time to shop, it may be worthwhile to
reorganize entries for convenience (all the dairy items together, all the fresh fruits and
vegetables, and so on).
    Finally, the WMS tracks the assembly of each customer order.
    The scope of WMS is growing, as it acquires new responsibilities, such inducting newly arrived product and allocating available locations, coordinating the assembly of customer orders to meet shipping schedules, tracking productivity of workers, and so on. It may even talk to other specialized software such as Yard Management Systems (YMS), which coordinates the movement of full and empty trailers in the yard (a sort of warehouse of trailers). Finally, the WMS may provide summary data to an even larger Supply Chain Management System (SCMS) that plans and coordinates inventory levels and transportation from manufacturer to customer.
    It is thanks to the control afforded by software systems such as WMS that the pace of the supply chain has accelerated so much during the last 20 years. Not so very long ago any customer order was accompanied by the warning “Please allow six to eight weeks for delivery”. No one would put up with such service today. Precisely controlled product moves faster, which means that customers get better service, and with less inventory in the system.