Mathematics
Spline Interpolation and Its Role in Numerical Analysis
Quick fact
Spline interpolation avoids the wild oscillations that plague high-degree polynomial interpolation by using low-degree pieces (often cubics) joined smoothly, and its error can be made arbitrarily small by refining the knot spacing.
Why this is interesting
Ever tried to draw a smooth curve through scattered points, only to get a wiggly mess? Spline interpolation is the mathematical trick that keeps curves smooth without the chaos.