Design Nomenclature / Form & Geometry
Edge loop
Also called loop, edge flow
A path of edges that continues straight through every four-valence vertex it meets, turning neither left nor right, and usually closing on itself. Loops run along the surface's structural direction and terminate at poles, boundaries, and n-gons. They are the unit of insertion: adding one adds an entire band of geometry at once.
In practice
'Good edge flow' means loops that follow the form's creases and the deformation's hinges — a loop around an eye, a loop at an elbow. That is a claim about anatomy, not about topology in the mathematical sense.