add no value to the finished product or service or to the parent organization (see Table 1). Whereas each element in the table can be a significant source of waste in itself, linkages between elements sometimes create a cascade of waste (the so-called domino effect). For example, a faulty load balancer (waste element: Defects) that increases web server response time may cause a lengthy wait for users of a web application (waste element: Waiting), resulting in excessive demand on the customer support call center (waste element: Excess Motion) and, potentially, subsequent visits by account representatives to key customers’ sites to quell concerns about the service availability (waste element: Transportation). In the meantime, the company's most likely responses to this problem — for example, introducing additional server capacity and/or redundant load balancing software), and hiring extra customer support agents — may contribute yet more waste elements (Overprovisioning and Excess Inventory). Principles Value streams In IT, value streams are the services provided by the IT function to the parent organization for use by customers, suppliers, employees, investors, regulators, the media, and any other stakeholders. These services may be further differentiated into: Business services (primary value streams). Examples: point-of-sale transaction processing, ecommerce, and supply chain optimization IT services (secondary value streams). Examples: application performance management, data backup, and service catalog The distinction between primary and secondary value streams is meaningful. Given Lean IT's objective of reducing waste, where waste is work that adds no value to a product or service, IT services are secondary (i.e. subordinate or supportive) to business services. In this way, IT services are tributaries that feed and nourish the primary business service value streams. If an IT service is not contributing value to a business service, it is a source of waste. Such waste is typically exposed by value-stream mapping. Value-stream mapping Lean IT, like its lean manufacturing counterpart, involves a methodology of value-stream mapping — diagramming and analyzing services (value streams) into their component process steps and eliminating any steps (or even entire value streams) that do not deliver value. Flow Flow relates to one of the fundamental concepts of Lean as formulated within the Toyota Production System — namely, mura. A Japanese word that translates as “unevenness,” mura is eliminated through just-in-time systems that are tightly integrated. For example, a server provisioning process may carry little or no inventory (a waste element in Table 1 above) with