This document summarizes a presentation about building augmented reality (AR) and virtual reality (VR) experiences in the browser. It discusses using the A-Frame framework to create VR galleries and art displays. It also covers adding AR capabilities using AR.js markers and the WebXR Device API. The presentation emphasizes optimization techniques for images, 3D models, and animations to ensure good performance for AR and VR experiences in the browser. Code examples and links are provided to demonstrate different AR and VR concepts discussed.