The much-discussed "crow's feet" describes the wrinkles seen at the outer corner of the eye, which extend towards the temples.
They are named like that because they resemble the shape of a goose or crow's foot.
"Crow's feet" belong to expression wrinkles, which are the result of repeated movements that activate the tiny muscles in the area, creating small folds.
Wrinkles follow the natural aging process in which collagen and elastin, the two main proteins of firmness, gradually decrease.
The skin around the eyes is much thinner than other areas of the face, so premature signs of aging appear there.