This is the collection of all ridges that stick out from other objects. More precisely, each instance of ridge is a long and thin, bilaterally symmetrical, external part of some larger tangible object. A swatch of corduroy, the edge of a dime, and a Ruffles brand potato chip all have ridges as parts.

For those ridges that are TopographicalFeatures, see the specialization ridge-hill. And for the top of such a ridge, see ridge line.