BLEND file extension is used by files created by Blender software program. Blender is a tool used for modeling and rendering 3D images and animations. BLEND file doesn’t store the actual 3D image or animation, but only a project of such.

Blender saves all data needed for creating an image or animations in BLEND project files. Data include information about objects, their properties, relations with other objects, and audio data. Animation data also contain informations regarding the animation frames.