The determinant — 3Blue1Brown · Essence of Linear Algebra Ch.6

Watch the unit square stretch, squish, and flip — its area is the determinant.

Matrix
det = 1
Identity — det = 1. The unit square (orange outline) stays exactly the same square. No stretching, no squishing, no flipping.

The orange square always starts as the 1×1 unit square sitting on î and ĵ — watch how its area changes