# Extended Reality: Types and Applications
## 1 Introduction  
Extended reality (XR) is an intensively developing technology that provides us with useful tools for displaying and interacting with various information. It provides virtual and augmented ways to interact with information in the real and virtual worlds [1]. Extended reality includes virtual reality (VR) where the user sees only the virtual world and does not see the real one, augmented reality (AR) where the user sees computer graphics superimposed on the real world, and a mixed reality (MR) where the user can additionally see and interact with both real and virtual objects simultaneously, all of which use computer graphics to visualize any information. The active development of these technologies finds their application in various fields, including use in combination with robots. These technologies offer new opportunities for the visualization of equipment before installation, simulating and controlling its operation, which makes them in demand in various industries ranging from manufacturing to entertainment. One of the key areas of application is education and training [2]. XR technologies allow us to create interactive environments both in the virtual world and complement the real one. This allows safe simulation of real conditions for practical training. In robotics, such approaches are used to train operators and engineers to work with complex systems. For example, XR can improve the operator's understanding of the tasks assigned to them in remote work [3], the robot's task in path planning for finding the shortest way avoiding all obstacles [4], and simulation of the robot movements in virtual environment, making the human-machine interface (HMI) more user-friendly and natural [5]. This can improve the speed, quality, and safety of work, including tasks with robots and their path planning, which is truly relevant formodern factories [6]. Augmented reality can improve the training process for a new employee. For example, it can show the assembly instructions for the mechanisms and their settings, as well as all the necessary documentation [7], which will increase the speed of training and reduce the likelihood of errors. In production or service centers, these systems can show equipment parameters such as temperature, pressure, percentage of wear of parts, date of previous or predictive replacement, and which part will need maintenance, which can speed up maintenance and diagnostics thanks to interactive instructions, pre-ordered parts or consumables, and clear maintenance planning, which is part of Industry 4.0 systems [7]. The implementation of augmented reality systems, as well as systems that improve safety in production, allows us to approach Industry 5.0 systems, where a person is part of the working system and interacts with an automated production line and robots. The use of VR head-mounted display (HMD) technology improves spatial belief when teleoperating a robot [5], since the operator sees a stereo image and controls the view by simply turning his head, thereby allowing both hands to be used for control [6; 8]. Teleoperation is truly relevant in areas dangerous to humans, such as deep-sea work, work in space, and demining or rescue operations. Teleoperation is used in sapper robots and reconnaissance robots, where it is necessary to ensure the safety of the mission [9], as well as in robotic surgery, where the surgeon remotely controls the robot that performs the operation [10]. The main problem is that programming robots often takes a lot of time and requires high qualifications [11]. The main way is to manually control or input coordinates step by step and train the robot to create a path. Some mobile robots can use a 2D floor plan to create a map for navigation. Navigation is very important for the correct localization of mobile robots.