IT controlling is established as a tool for controlling information technology. The job description of the IT controller has changed only moderately over a long period of time. It was mainly associated with IT budgeting, IT portfolio management, IT cost planning, accounting and controlling. However, digitalization has brought movement in goals, contents and methods. New topics such as digital strategy management, cloud controlling, data science, etc. are being discussed. The task profile is changing away from pure IT cost analysis to the management of the digitization strategy with a focus on strategic IT portfolio management. Some voices are already talking about "smart controlling" or "digital controlling".  This book presents an IT controlling concept for the digital age and explains the relevant methods in a practical way.