Blender is a free 3D graphics application that can be used for modeling, UV unwrapping, texturing, rigging, water and smoke simulations, skinning, animating, rendering, particle and other simulations, non-linear editing, compositing, and creating interactive 3D applications, including video games, animated film, or visual effects.
Blender's features include advanced simulation tools such as rigid, realistic body, fluid, cloth and softbody dynamics, modifier-based modeling tools, powerful character animation tools, a node-based material and compositing system and Python for embedded scripting.
Released as free software under the GNU General Public License, Blender is available for a number of operating systems, including GNU/Linux, Mac OS X, and Microsoft Windows.

Features:

Blender has a relatively small installation size and runs on several popular computing platforms, including Linux, Mac OS X, and Microsoft Windows, along with FreeBSD, IRIX, NetBSD, OpenBSD and Solaris. Unofficial ports are also available for AmigaOS 4, BeOS, MorphOS , Pocket PC and SkyOS.[7]  Though it is often distributed without documentation or extensive example scenes, the software contains features that are characteristic of high-end modeling software.Among its capabilities are:

• Support for a variety of geometric primitives, including polygon meshes, fast subdivision surface modeling, Bezier curves, NURBS surfaces, metaballs, digital sculpting, and outline fonts.
• Versatile internal rendering capabilities and integration with YafaRay, a Free Software ray tracer.
• Keyframed animation tools including inverse kinematics, armature (skeletal), hook, curve and lattice-based deformations, shape keys (morphing), non-linear animation, constraints, vertex weighting, soft body dynamics including mesh collision detection, LBM fluid dynamics, Bullet rigid body dynamics, particle-based hair, and a particle system with collision detection.
• Modifiers to apply non-destructive effects.
• Python scripting for tool creation and prototyping, game logic, importing and exporting from other formats such as OBJ, FBX, DXF, COLLADA, task automation and custom tools.
• Basic non-linear video/audio editing and compositing capabilities.
• Game Blender, a sub-project, offers interactivity features such as collision detection, dynamics engine, and programmable logic. It also allows the creation of stand-alone, real-time applications ranging from architectural visualization to video game construction.
• A fully-integrated node-based compositor within the rendering pipeline