This graduate course introduces students to the theory and practice of extended reality (XR), encompassing virtual reality (VR), augmented reality (AR), and mixed reality (MR) technologies. Students explore the conceptual foundations of immersive environments, including perception, presence, and interaction design in three-dimensional spaces. The course examines current XR platforms, authoring tools, and the design principles that guide the creation of effective and usable immersive experiences. Students develop hands-on skills through project work that integrates design thinking with XR prototyping.