Mathematics
Quaternions vs. Matrices for Representing Rotations in 3D Space
Quick fact
Quaternions require only 4 numbers to represent a rotation, while a rotation matrix needs 9—yet quaternions avoid a notorious failure mode called gimbal lock that can make Euler-angle systems freeze up.
Why this is interesting
You can rotate an object in 3D using a 3×3 matrix or a 4‑number quaternion. Both do the same job, so why do animators and spacecraft engineers ditch matrices for quaternions?