XR spans a continuum from Augmented Reality (AR), through Mixed Reality (MR), to full Virtual Reality (VR), with increasing levels of immersion and interaction. VR is defined by three key elements: immersion, interaction, and presence. Immersion refers to the sensory perception of being inside a virtual environment through technological interfaces, creating the illusion of physical entry into the digital world. Interaction is the user’s ability to influence the virtual world and receive feedback, which enhances realism, agency, and engagement. Presence, distinct from immersion, is the psychological sense of “being there,” even without full sensory input—comparable to the absorption felt when reading a novel or watching a film. While presence depends on immersion and interaction, it also requires the user’s active suspension of disbelief to be fully realized. To meet the demands of interactive experiences, immersion must be delivered through 3D graphics rendered in real time. While 360-degree videos are considered a form of VR, they offer minimal interactivity.

Virtual performers in XR include avatars and embodied agents. Avatars are digital representations of real individuals, animated through motion capture systems that translate a performer’s gestures and movements into a virtual character. These avatars can navigate virtual space, express a range of emotions, and participate in immersive narratives. Embodied agents, by contrast, are autonomous virtual characters designed with simulated perception, cognition, and behavior. They operate based on predefined scripts or procedural logic, and can include features such as speech synthesis and gesture animation to support interactive or responsive performance dynamics.

Creating convincing and expressive virtual humans relies on key 3D animation techniques enabling natural movement including facial expressions, essential for emotional nuance. Together, these technologies support compelling digital performances, expanding the language of theatre and performance into virtual and hybrid spaces.