Simulates the movements and reactions of objects using real-world concepts like mass, velocity, constraints, and forces (like drag, gravity, and friction). Makes use of extremely optimized algorithms for collision detection, physics calculations, geometry management, and more.

Articles:

Notable open-source libraries:

Commercial libraries:

If you're looking to do physical-based simulations, also take a look at game development and VFX environments like Unity, Unreal, and Houdini for their built-in physics engines.