A brief history of the evolution of CT scanners from the time X-ray tomography was conceived till the present-day computed tomography (CT) scanners, makes interesting reading. This chapter includes some of the main events leading to the evolution of the current generation of CT scanners. Additionally, the chapter also introduces the readers to the various types of CT scanners available and the way they work. Readers may want to know more about scanners. A few references are provided for those with a historical and technical bend of mind.