What it measures: Straight-line distance between two points in space, like measuring with a ruler.
When to use: Image embeddings, spatial data, when both direction and magnitude matter.
Math insight: Treats each dimension equally and measures actual "distance" in the mathematical space.
Example: Measuring the difference between two product features where both the type and intensity of features matter.
Range: 0 to ∞ (closer to 0 = more similar)
