The 3D Viewer in Windows 10 is a built-in app that allows users to view and interact with 3D models and images. It supports a variety of 3D file formats, including .fbx, .3mf, .obj, .ply, and .stl, making it a versatile tool for visualizing 3D content. With the 3D Viewer, users can rotate, pan, and zoom in on 3D models, as well as apply various lighting and rendering effects to enhance the viewing experience. Additionally, the app supports mixed reality viewing, allowing users to place 3D models in their physical environment using a compatible headset. The 3D Viewer is also useful for 3D printing, as it provides tools for checking and preparing 3D models for printing. Overall, the 3D Viewer in Windows 10 is a powerful and convenient tool for working with 3D content, whether it's for artistic, educational, or professional purposes.