What is extended reality (XR)?

XR is the umbrella term for virtual, augmented and mixed reality. This page sets out where each one sits, what a headset has to do to hold a room together, and when the format is worth its cost.

A facilitator fits a first-time user with a PTR-branded Meta Quest 2 headset at a live event, PTR's robot-character poster in the background. — A first-time user receives a headset fitting.

Extended Reality (XR) is an umbrella term for 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), and future spatial technologies 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

Paul Milgram and Fumio Kishino drew the line in 1994. Their continuum sorts any display by one measure: how much of what a person sees is physically present, and how much is virtual.

One term at the top, three ways of mixing the real room with a virtual one underneath it.

A facilitator explains the spectrum to two people standing where a plain gallery room gives way to a virtual landscape. A VR training scenario for what is extended reality. — A plain room giving way to a landscape.

Both ends of the line, in one room

Stand at one end and everything you see is the room you are in. Walk to the other and everything you see is virtual.

XR is the whole line, not a point on it. Spatial computing means working anywhere along it in three dimensions rather than on a flat screen.

VR, AR and MR on one spectrum

What each of the three actually does to what a person can see, and the kind of practice each one suits.

A guide stands among forms arranged. a first-person moment from PTR's immersive training showreel. — **Virtual Reality (VR).** Completely replaces the physical environment with a fully simulated world viewed through an enclosed headset.

A facilitator views a 3D structure. A VR training scenario for what is augmented reality. — **Augmented Reality (AR).** Keeps the physical environment visible while overlaying digital elements onto a screen or a transparent lens.

Two people display a figure partly hidden. A VR training scenario for what is mixed reality. — **Mixed Reality (MR).** Merges physical and digital so real and virtual objects coexist and interact in real time.

How XR works in practice

Every XR device does two jobs at once: track where the wearer is, and place digital content accurately in 3D space around them, with as little delay as possible.

A learner moves inside a tracked space. A VR training scenario for what is extended reality. — **Positional tracking.** Sensors and cameras follow where a user is looking and moving. Three degrees of freedom (3DoF) tracks head rotation from a fixed point; six degrees of freedom (6DoF) also tracks movement through space, so stepping forward or crouching moves the view with you.

Two people inspect the headset lenses. A VR training scenario for what is virtual reality. — **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 lenses or video passthrough, where external cameras put the real world on internal screens.

A facilitator stands among sound forms. A VR training scenario for what is extended reality. — **Spatial audio.** Sound is positioned in 3D so noises appear to come from specific places, which is how a person finds a speaker or an object without being told where to look.

Two people test a controller beside a switch. A VR training scenario for what is virtual reality. — **Input and control.** Handheld controllers, bare-hand tracking, voice and eye tracking. Meta's own developer documentation describes hand tracking as an input method alongside controllers, not instead of them, for tasks that need precision.

What the tracking is for

Rotation on the spot, a model held at the size it really is, and a digital layer added to something physically in front of you.

A seated learner demonstrates head rotation. A VR training scenario for what is extended reality. — A seated learner demonstrates head rotation.

Two people inspect an anatomy form. A VR training scenario for what is extended reality. — Two people inspect an anatomy form.

Three people display a visual layer. A VR training scenario for what is extended reality. — Three people display a visual layer.

What it feels like to use XR

Immersion is the technical sensation of being surrounded by digital media. Presence is the psychological one: the feeling of actually being in the place.

A man wearing a Meta Quest 3 headset raises two controllers while Peter, PTR's white and gold in-VR robot guide, floats beside him outdoors among bamboo and leafy plants — PTR's guide Peter floats beside a Quest user.

The first two minutes decide it

In VR the brain adapts quickly, and simulated objects begin to feel solid and correctly sized. In AR and MR the real room stays visible, and the digital additions sit on the floor, the table or the equipment in front of you.

Latency is the gap between moving and the display catching up. The shorter it is, the more the movement feels like your own.

"Virtual Reality offers a unique and powerful training tool that can immerse individuals in realistic, high-pressure environments without the associated risks."

Simon Lowe, PTR's CEO, mid-sentence at a lectern. Simon Lowe
CEO, People Tech Revolution. Let's be prepared, Global Best Practice Group, August 2024

Where XR is commonly used

Across these sectors XR is used to practise difficult tasks, inspect full-scale designs, and bring people closer to places and objects that are hard to reach.

A public official wears a VR headset during a live PTR demonstration, part of the government and public-sector engagement work PTR's VR training supports. — PTR demonstrates its VR work to government.

The same question in every sector

Can people practise the thing that goes wrong, often enough to get good at it, without anyone paying for the mistake? That is what decides whether a sector reaches for XR at all.

Sector by sector

The tasks XR is used for in workforce training, healthcare, education, design and public engagement, and the scene each one looks like.

A technician works beside assembly cues. A first person VR training scenario for what is augmented reality, seen through the headset. — **Workforce training and procedural practice.** Staff rehearse emergency procedures, equipment maintenance and hazardous tasks without physical danger or equipment downtime.

A man wearing a VR headset stands at a hospital bedside facing a floating panel of three choices, a patient in the bed beyond — **Healthcare and clinical education.** Clinicians and students study anatomy, rehearse procedural workflows and practise patient communication in a spatial simulation.

Three people inspect a molecular model. A VR training scenario for what is augmented reality. — **Education and research.** 3D models make scientific concepts, historical artefacts and structures visible at true size when the real thing is out of reach.

Two people inspect a machine structure. A VR training scenario for what is mixed reality. — **Design, engineering and spatial planning.** Teams walk a full-scale digital prototype of a building, vehicle or facility and find the clashes before anything is built.

A visitor stands beside an exhibition layer. A first person VR training scenario for what is augmented reality, seen through the headset. — **Public engagement and exhibitions.** Cultural institutions and event teams add an interactive layer to an object so a visitor can see the part of the story a label cannot carry.

One method, three different rooms

A boardroom, a depot and a crew shed. The room changes and the scenario changes with it. What someone has to say does not get any easier.

A participant wearing a headset stands at the end of a seminar table addressing four seated simulated colleagues of different ages and backgrounds. — A speaker addresses four colleagues around a table.

A driver wearing a headset stands in a transport depot facing a simulated supervisor in a plain high-visibility vest. — A driver faces a supervisor in a depot.

A crew member wearing a headset stands facing two seated simulated colleagues, one laughing and one looking away. — A crew member faces laughter; another looks away.

XR in practice at PTR

Most of PTR's XR work is virtual reality. Mater's own program evaluation reported that 93% of participants enjoyed the experience and 96% wanted more VR-based learning in future programs.

Download the Mater case study PDF

A clinician in a headset at a hospital bedside, the ward fully simulated around the conversation. — Inside Mater's Speaking with Good Judgement build.

Mater Education, Speaking with Good Judgement

Mater Education, part of the Mater hospital group in Queensland, brought its staff communication program into a branched VR experience with PTR, recreating real Mater rooms so staff could rehearse hard feedback conversations and watch the consequences of each choice play out.

It ran face to face for more than 60 staff. Read the full case study

Where PTR sits on the spectrum

Virtual reality is most of the work. Augmented reality is a build you can point a phone at today, and mixed reality keeps the real room in view while it runs.

Everyday Inclusion title card with three characters linking arms: a woman in a patterned scarf, a woman in a maroon shirt and a man in a green jumper. — **VR, delivered work.** Central Coast Council's disability-awareness VR has run more than 200 times, and Everyday Inclusion, co-designed with Cornell University and Angela Winfield, has run since 2018. The PTR VR Library

A printed model gains an augmented-reality layer, seen through a phone held over the page. — **AR, live browser demo.** Point a phone camera at the PTR business card and the build opens in the browser, with nothing to install. Try the AR Business Card

A facilitator checks anchored wall forms. A VR training scenario for what is mixed reality. — **MR, anchored in the real room.** Mixed reality keeps the room visible and holds holographic people and objects inside it, so the practice happens where the work happens. What is Mixed Reality?

Common confusions about XR

What people expect XR to be when they first hear the word, and what it turns out to be once they use it.

Three people display a guidance arrow. A VR training scenario for what is augmented reality. — **"XR is just another name for VR."** VR is one part of the XR family. An organisation using phone-based AR for equipment inspection is using XR just as much as one running full VR simulation in headsets.

Two people display dotted planes on a tablet. A VR training scenario for what is augmented reality. — **"XR always means a heavy headset."** Many VR and MR experiences do use headsets, but AR is widely reached through ordinary smartphones, tablets and lightweight glasses.

A facilitator turns over a feedback card. A VR training scenario for AI training and roleplay. — **"XR replaces traditional training."** It works best beside existing methods, on the tasks where hands-on practice is expensive, hazardous or hard to repeat. The debrief afterwards is still where most of the learning lands.

Three people compare three different spaces. A VR training scenario for XR and AI concepts explained simply. — **"There is a settled line between VR and MR."** Even researchers disagree. A 2019 ACM CHI study interviewed ten AR and VR experts and reviewed 68 papers, and found at least six competing notions of what mixed reality means. Use the categories as shorthand, and ask a vendor which one they mean.

Is XR the right fit?

A headset is a cost and a constraint as well as a capability. These are the questions that settle it before anyone builds anything.

A vast bright circular atrium with a round open skylight, trailing ivy and curved white walls, one of the PTR VR Library's settings — A bright atrium under an open skylight.

More immersive is not more useful

The test is what the task needs: how often it is done, what it costs to get wrong, and how much of the real room a person has to keep watching while they do it.

Where it fits, and where it does not

The conditions that make a build worth it, and the ones that mean a simpler format will serve the same people better.

An instructor points along a route. A first person VR training scenario for choosing the right technology, seen through the headset. — A strong fit when Hands-on practice is expensive, hazardous or hard to repeat. People need to rehearse a difficult conversation or procedure before doing it for real. The task depends on spatial understanding. The same scenario has to reach a large team consistently, in short repeatable sessions.

A learner demonstrates limited head movement. A VR training scenario for immersive VR training questions answered. — Not the right fit when A rarely performed task will not repay the setup cost. Headsets are shared and some users feel motion discomfort; cybersickness research back to 2000 documents causes and mitigations, not a cure. Enclosed VR removes the real room, so it is wrong where people must keep watching their surroundings. Weekly-changing content is better served by a simpler format.

An abstract virtual space: soft pale gradient walls, gentle floating pale-blue geometric shapes at different depths, nothing else at all — An abstract space with nothing else in it.

The short version

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. MR lets 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.

See how each one is applied, sector by sector, on the XR overview →