This article describes basics about Lean IT. The roots of Lean IT are - as the name suggests - in Lean Management. The basic principles of Lean Management had been developed in Toyota's Production System, that was built back in the 40s of last century.
Lean IT is really nothing new, but as an application or adaptation of the basic principles of Lean Management to software development and maintenance the topic not commonly known. The two key elements of Lean IT are the avoidance of waste and continuous improvement process. [1, 2, 3]
The introduction of lean in a company is also known as Lean Transformation Program. Because it is a big organisational and cultural change, Lean IT is not only the introduction of a single methodology. A Lean Transformation requires actions in several dimensions. The approach of McKinsey considers the following example (4 +1) dimensions: 
Steven C. Bell describes in his book 'Lean IT, Enabling and Sustaining Your Lean Transformation' following nine principles and/or elements of Lean IT: 
Figure 1 shows some of the most important dependencies and relations.
Figure 1: Lean IT principles overview and dependencies
Agile software development methodologies (e.g. SCRUM, XP) and Lean IT are very similar and this is no coincidence, because many of the agile methods and paradigms have their roots in Lean Management.There are some important differences:
Despite all the differences, both approaches have in common is that they try to (i) increase productivity and customer orientation (ii) by means of a continuous improvement process (iii) to achieve increased customer benefits.
 Lean Management; Wikipedia; (Stand 2. August 2011);
 Lean IT; Wikipedia; (Stand 2. August 2011);
 The time is right for lean in payments; (2009);