Blender is the open source software for 3D modeling, animation, rendering, post-production, interactive creation and playback.

Interface
Revolutionary non-overlapping and non-blocking UI delivers unsurpassed workflow
Flexible and fully configurable window layout with as many screen setups as you prefer
Powerful built-in database system allowing instances,scene management and dynamic linking multiple project files,Anti-aliased fonts with international translation support
Windows for animation curves/keys, outliner, schematic scene diagram, non-linear video sequence editing, character animation action editor, non-linear animation mixer, image/UV editing, file/image selection and file management,Built-in text editor for annotations and editing Python scripts
Consistent interface across all platforms, Undo support on all levels
Modeling
A range of 3D object types including polygon meshes, NURBS surfaces, bezier and B-spline curves, metaballs, vector fonts (TrueType, PostScript, OpenType) Mesh modeling based on vertex, edge and/or face selection
'Smooth proxy' style catmull-clark subdivision surfaces with optimal iso-lines display and sharpness editing
Editing functions such as extrude, bevel, cut, spin, screw, warp, subdivide, noise, smooth Soft selection editing tools for organic modeling, Python scripting access for custom tools, Boolean mesh functions
Animation
Armature (skeleton) deformation with forward/inverse kinematics, auto skinning and interactive 3D paint for vertex weighting, Non-linear animation mixer with automated walkcycles along paths
Vertex key framing for morphing, with controlling sliders
Character animation pose editor, Constraint system, Animatable lattice deformation
'Ipo' system integrates both motion curve and traditional key-frame editing
Audio playback, mixing and editing support for sound synchronisation
Python scripting access for custom and procedural animation effects
Rendering
Very fast inbuilt raytracer, Environment maps, halos, lens flares, fog
Integral support for the famous Yafray render engine,Procedural Textures,Ambient Occlusion,Radiosity solver
Oversampling, motion blur, post-production effects, fields, non-square pixels
Various surface shaders such as Lambert, Phong, Oren-nayar, Blinn, Toon
Edge rendering for toon shading, UV texture editor with various mesh unwrap
Export scripts available for external renderers such as Renderman (RIB), Povray, Virtualight
Realtime 3D/game creation
Graphical editor for defining interactive behavior without programming
Collision detection and dynamics simulation
Python scripting API for sophisticated control and AI, fully defined advanced game logic
Supports all OpenGLTM lighting modes, including transparencies, Animated and reflection-mapped textures
Playback of games and interactive 3D content without compiling or preprocessing
Audio, using the SDL toolkit, Multi-layering of Scenes for overlay interfaces
Files
Save all scene data in a single .blend file, .blend format supports compression, digital signatures, encryption, forwards/backwards compatibility and can be used as a library to link to from other .blend files
Read / Write TGA, JPG, PNG, Iris, SGI Movie, IFF, AVI and Quicktime GIF, TIFF, PSD, MOV (Windows and Mac OS X)
Native import and export for DXF, Inventor and VRML files, with python scripts available for many other 3D formats
Create stand-alone executables containing interactive 3D content or play back with the 3d web browser plugin