this tendency, recessions initially provoke aggressive (and sometimes panic-ridden) actions such as deep discounting, fire sales of excess inventory, wage freezes, short-time working, and abandonment of former supplier relationships in favor of less costly supplies. Although such actions may be necessary and prudent, their impact may be short-lived. Lean IT can expect to garner support during economic downturns as business leaders seek initiatives that deliver more enduring value than is achievable through reactive and generalized cost-cutting. Proliferation of online transactions IT has traditionally been a mere support function of business, in common with other support functions such as shipping and accounting. More recently, however, companies have moved many mission-critical business functions to the Web. This migration is likely to accelerate still further as companies seek to leverage investments in service-oriented architectures, decrease costs, improve efficiency, and increase access to customers, partners, and employees. The prevalence of web-based transactions is driving a convergence of IT and business. In other words, IT services are increasingly central to the mission of providing value to customers. Lean IT initiatives are accordingly becoming less of a peripheral interest and more of an interest that is intrinsic to the core business. Green IT Though not born of the same motivations, lean IT initiatives are congruent with a broad movement towards conservation and waste reduction, often characterized as green policies and practices. Green IT is one part of this broad movement. Waste reduction directly correlates with reduced energy consumption and carbon generation. Indeed, IBM asserts that IT and energy costs can account for up to 60% of an organization's capital expenditures and 75% of operational expenditures. In this way, identification and streamlining of IT value streams supports the measurement and improvement of carbon footprints and other green metrics. For instance, implementation of Lean IT initiatives is likely to save energy through adoption of virtualization technology and data center consolidation. Challenges Value-stream visualization Unlike lean manufacturing, from which the principles and methods of Lean IT derive, Lean IT depends upon value streams that are digital and intangible rather than physical and tangible. This renders difficult the visualization of IT value streams and hence the application of Lean IT. Whereas practitioners of lean manufacturing can apply visual management systems such as the kanban cards used in the Toyota Production System, practitioners of Lean IT must use enterprise IT management tools to help visualize and analyze the more abstract context