AR, VR, and MR, collectively referred to as XR, are becoming ubiquitous for human computer interaction with limitless applications and potential use. This course examines advances on real-time multi-modal XR systems in which the user is 'immersed' in and interacts with a simulated 3D environment. The topics will include display, modeling, 3D graphics, haptics, audio, locomotion, animation, applications, immersion, and presence and how they interact to create convincing virtual environments.