The Visualization Toolkit (VTK) is an open-source, freely available software system for 3D computer graphics, image processing and visualization. VTK consists of a C++ class library and several interpreted interface layers including Tcl/Tk, Java, and Python. Kitware, whose team created and continues to extend the toolkit, offers professional support and consulting services for VTK. VTK supports a wide variety of visualization algorithms including: scalar, vector, tensor, texture, and volumetric methods; and advanced modeling techniques such as: implicit modeling, polygon reduction, mesh smoothing, cutting, contouring, and Delaunay triangulation. VTK has an extensive information visualization framework, has a suite of 3D interaction widgets, supports parallel processing, and integrates with various databases on GUI toolkits such as Qt and Tk. VTK is cross-platform and runs on Linux, Windows, Mac and Unix platforms. VTK employs Kitwarea€™s Quality Software Process (CMake, CTest, CDash, and CPack) to build, test and package the system. Making VTK a cross-platform application dependant on test-driven development and extreme programming and enabling the application to produce high-quality, robust code. VTK is used world-wide in commercial applications, research and development, and is the basis of many advanced visualization applications such as: ParaView, VisIt, VisTrails, Slicer, MayaVi, and OsiriX. The Origins of VTK VTK was originally written as part of a textbook The Visualization Toolkit An Object-Oriented Approach to 3D Graphics. Will Schroeder, Ken Martin, and Bill Lorensen, three graphics and visualization researchers, wrote the book and companion software on their own time beginning in December 1993, and with legal permission from their then employer GE Corporate R&D. The motivation for the book was to collaborate with other researchers and develop an open-framework for creating leading edge visualization and graphics applications. VTK grew out of the authors' experience at GE, particularly with their experience with the LYMB object-oriented graphics system. Other influences included the VISAGE visualization system developed by Schroeder et. al, the Clockworks object-oriented computer animation system developed at RPI, and the very successful object-oriented modeling book Object-Oriented Modeling and Design on which Bill Lorensen was co-author. After the core of VTK was written, users and developers around the world began to improve and apply the system to real-world problems. In particular, GE Medical Systems and other GE businesses graciously contributed to the system. Some researchers, such as Dr. Penny Rheinghans began to teach with the book. Other early supporters included Jim Ahrens at Los Alamos National Labs, and unnamed, but generous oil and gas supporters. In recent years, Sandia National Labs have been strong supporters and co-developers with particular focus on adding information visualization to VTK. To support what was becoming a large, active and world-wide VTK community Ken and Will, along with Lisa Avila, Charles Law and Bill Hoffman left GE Research to found Kitware, Inc. in 1998. Since that time, hundreds of additional developers have created what is now the premier visualization system in the world today.