Under-eye bags are the mild swelling or puffiness that forms beneath the lower eyelids, often giving the face a tired or aged appearance. They develop due to weakened skin and muscles around the eyes, allowing fat to shift forward and fluid to accumulate. Common causes include aging, genetics, poor sleep, allergies, and lifestyle factors such as excessive salt intake or dehydration. Risk factors such as sun exposure and smoking can accelerate skin aging, making under-eye bags more pronounced. While not a medical concern, under-eye bags can impact self-confidence and make individuals look fatigued even when they feel well-rested.