The Wavefront .OBJ file format is a geometry definition file format first developed by Wavefront Technologies for its Advanced Visualizer animation package. It has become a widely adopted open file format for 3D models. The OBJ file format stores 3D object data, representing the surface geometry using vertices, texture coordinates, vertex normals, and faces (polygons). It can also store material properties, although these are typically stored in a separate .MTL (Material Template Library) file that the .OBJ file references. The format is primarily used for static 3D models and does not support animation or skeletal rigging directly. It's a simple, text-based format, making it relatively easy to parse and edit. Because of its simplicity and widespread adoption, it's often used as an interchange format between different 3D modeling and rendering applications. While newer formats offer more advanced features like animation and complex material definitions, OBJ remains a popular choice for its compatibility and ease of use, especially for simpler models or as a common denominator for transferring geometry between different software packages. The format supports both polygonal and free-form geometry. The .OBJ file itself is a plain text file that contains a list of vertices, normals, texture coordinates, and faces, along with optional material references.