BLEND is the native project file format for Blender, the popular open-source 3D creation suite. A BLEND file stores everything in the scene, including models, animations, textures, lighting, and even the UI layout of the editor. It is a binary format that is backward and forward compatible across many Blender versions. Sample BLEND files are used to test Blender's internal data handling and linked libraries. Developers use them to verify that project data is saved and loaded without corruption. They are also used to test render farms and automation scripts that render Blender scenes via the command line.