Software systems are used to support the warehousing processes. Starting as Inventory Control Systems, today’s
WMS contain much more functionality and optimisation routines. Order picking as the process of retrieving
products from storage in response to a specific customer request is considered as a core function within a WMS.
Experiences from practice show that about a half of the total operating expenses of a warehouse is spent by order
picking (see Tompkins et al (2003)). This is caused by the complexity and the labour intensity of order picking
processes. Given this economic importance, the decision support for planning and controlling the order picking
processes within a WMS is a central task, and WMS suppliers are seeking to integrate functionality for increasing
the productivity and optimising the order picking operation. This kind of decision support will be named the order
picking strategy later on.