What is extended reality (XR)?
Extended Reality (XR) is an umbrella term that covers all immersive technologies that alter, enhance, or replace the user's view of the physical world with digital content. It brings together Virtual Reality (VR), Augmented Reality (AR), and Mixed Reality (MR), as well as future spatial technologies that sit anywhere along the spectrum between purely physical environments and fully digital simulations. The "X" serves as an algebraic variable representing any current or upcoming technology that blends physical and digital spaces.
The reality-virtuality spectrum
To understand XR, it helps to look at the reality-virtuality continuum, a concept introduced by researchers Paul Milgram and Fumio Kishino in 1994 to classify how much of what a person sees is physically real versus computer-generated.
XR spans three core pillars:
- Virtual Reality (VR): Completely replaces the physical environment with a simulated, computer-generated world viewed through an enclosed headset.
- Augmented Reality (AR): Keeps the physical environment visible while overlaying digital elements (such as text, images, or 3D graphics) onto a screen or transparent lens.
- Mixed Reality (MR): Merges physical and digital environments so that real and virtual objects can coexist and interact dynamically in real time.
Together, these technologies form the foundation of spatial computing (computing where digital content is positioned and interacted with in three-dimensional space rather than confined to a flat two-dimensional screen).
How XR works in practice
XR systems combine specialised hardware and software to track user movement and display digital content accurately in 3D space.
Key technical components include:
- Positional tracking: Devices use sensors and cameras to track where a user is looking and moving. This is often described as degrees of freedom (DoF). Three degrees of freedom (3DoF) tracks head rotation (looking up, down, left, or right from a fixed point), while six degrees of freedom (6DoF) also tracks movement through space (stepping forward, backward, crouching, or walking).
- Display optics: Headsets use high-resolution micro-displays and optical lenses to project images directly in front of the eyes. AR and MR devices use transparent optical lenses or video passthrough (using external cameras to display the real world on internal screens).
- Spatial audio: Sound is rendered in 3D so that noises appear to originate from specific physical locations, helping users locate virtual objects intuitively.
- Input and control: Users interact with digital content using handheld motion controllers, bare-hand tracking, voice recognition, or eye tracking. Meta's own developer documentation describes hand tracking as a way to let people use their hands as an input method alongside, not instead of, controllers, for tasks that need precision. Meta hand tracking documentation
What it feels like to use XR
Using an XR application creates varying degrees of immersion (the technical sensation of being surrounded by digital media) and presence (the psychological feeling of actually being inside a virtual space).
In fully immersive VR, the brain quickly adapts to the synthetic environment, making simulated objects and environments feel tangible and spatially convincing. In AR and MR, users remain grounded in their physical surroundings while experiencing digital additions that appear anchored to floors, tables, or equipment. Modern hardware aims to minimise latency (the slight delay between a user moving and the display updating) to ensure comfortable and natural movement.
Where XR is commonly used
Organisations across many sectors explore XR to support learning, operational efficiency, and engagement:
- Workforce training and procedural practice: Simulated environments allow staff to practise emergency procedures, equipment maintenance, and hazardous tasks in a controlled setting without physical danger or equipment downtime.
- Healthcare and clinical education: Medical professionals and students use spatial simulations to study anatomy, rehearse procedural workflows, and practise patient communication.
- Education and research: Academic institutions use 3D models to visualise complex scientific concepts, historical artefacts, and architectural structures that are difficult to access in person.
- Design, engineering, and spatial planning: Teams review full-scale digital prototypes of buildings, vehicles, or facilities before physical construction begins, helping identify design issues early.
- Public engagement and exhibitions: Cultural institutions and event organisers use interactive digital displays to present historical narratives and educational exhibits.
The same method in three rooms, as rendered illustrations of the uses listed above. Not footage from a client build.
XR in practice at PTR
Most of PTR's documented, delivered XR work is virtual reality. Mater Education, part of the Mater hospital group in Queensland, worked with PTR to bring its "Speaking with Good Judgement" staff communication program into a branched VR experience, recreating real Mater environments in 360 degrees so staff could rehearse difficult feedback conversations and see the consequences of different choices play out. Delivered face-to-face to more than 60 staff, Mater's own program evaluation reported that 93% of participants enjoyed the experience and 96% wanted more VR-based learning in future programs.
PTR builds mixed reality as well as VR and AR. MR keeps the real room visible and anchors holographic people and objects inside it, so the practice happens where the work actually happens rather than in a separate virtual place. What is Mixed Reality?
Common confusions about XR
VR is only one part of the XR family. An organisation using phone-based AR for equipment inspection is using XR just as much as one using headsets for full VR simulation.
While many VR and MR experiences use headsets, AR is widely accessed through standard smartphones, tablets, and lightweight smart glasses.
XR is most effective when used alongside existing learning methods, particularly for tasks where hands-on physical practice is expensive, hazardous, or difficult to repeat.
Even XR researchers disagree. A 2019 ACM CHI study interviewed ten AR/VR experts, reviewed 68 published papers, and found at least six partly competing notions of what "mixed reality" means. Treat category boundaries as useful shorthand, not a precise technical line.
Is XR the right fit?
XR is not automatically the better option just because it is more immersive:
- Hands-on practice is expensive, hazardous, or difficult to repeat, such as emergency procedures or equipment downtime.
- People need to rehearse difficult conversations or procedures safely before doing them for real.
- The task depends on spatial understanding: full-scale prototypes, anatomy, environments that are hard to access in person.
- The same scenario must reach a large team consistently, in short repeatable sessions.
- Cost versus frequency: headsets, controllers and custom builds carry real setup cost; a rarely performed task may not justify it.
- Comfort and hygiene: shared headsets, and some users experience motion discomfort. Cybersickness research back to 2000 documents causes and mitigations (lower latency, user-controlled movement), but not a universal cure.
- Situational awareness: enclosed VR removes peripheral vision and hearing of the real room; unsuitable where people must keep watching their surroundings for safety.
- One-off or fast-changing content: bespoke XR builds take time; weekly-changing or single-use content is often better served by a simpler format.
To explore how these technologies are applied across different sectors, visit the XR overview page.
XR is the umbrella term for VR, AR and MR. VR replaces what you see, AR adds to it while keeping the real world visible, and MR goes further by letting digital objects react to real surfaces. Which one fits a task depends mainly on how much of the physical world people need to stay aware of while they use it.
Sources and further reading
- A Taxonomy of Mixed Reality Visual Displays (Milgram and Kishino) - IEICE Transactions on Information and Systems, 1994
- A Survey of Augmented Reality (Azuma) - Presence: Teleoperators and Virtual Environments, MIT Press, 1997
- What is Mixed Reality? (Speicher, Hall and Nebeling) - ACM CHI Conference on Human Factors in Computing Systems, 2019
- A Discussion of Cybersickness in Virtual Environments (LaViola) - ACM SIGCHI Bulletin, 2000
- Hand Tracking Overview for Meta Quest in Unity - Meta Horizon OS Developers documentation
Mater Education case study · Central Coast Council case study · The PTR VR Library