Here are four of the most common forms of hyperpigmentation, each with their own unique characteristics:

Sun spots: These appear as small, flat, darkened areas on the skin, often with well-defined edges. They develop after sun damage on the face and body, and can vary in size from a few millimeters to several centimeters.

Age spots: Age spots are similar to sun spots but are generally more numerous and can become larger over time. They usually appear as rounded, dark brown or black patches on the hands, chest, face and arms, and their appearance often correlates with long-term sun exposure.

Post-inflammatory hyperpigmentation (PIH): These dark spots occur following an inflammatory event like acne or eczema. They can vary in color from red to brown to purple, and may have irregular borders. PIH often resolves with time but can be persistent if not treated.

Melasma: Melasma presents as large, irregularly shaped patches of dark skin, typically on the cheeks, forehead and upper lip. The patches are usually symmetrical on both sides of the face, and can range from light brown to dark brown. Melasma is often triggered by hormonal changes, such as pregnancy or birth control use, and is aggravated by sun exposure.