The darkening of skin under the eyes are called dark circles. They are commonly seen in older adults and people with darker skin color. The other causes include tiredness, oversleeping, eye strain, dehydration, sun exposure, and genetics.
Dark Circles - A Common Cosmetic Concern
Dark circles under the eyes can be aesthetically disturbing and make one look older. Learn about the various treatment options for dark circles.

Glasses Cause Dark Circles - An Insight
The skin under the eye is sensitive and can sometimes appear hollow, sunken, and dark. Read the article to know more.
Allergic Shiners: Causes, Symptoms, Diagnosis, and Treatment
Allergic shiners are allergic discoloration of the skin present beneath the eyes. Read the article to know more about it.