Hyperpigmentation is the name that skincare professionals give to patches of skin that become darker than surrounding areas of skin. The types of hyperpigmentation include age spots, melasma, and post-inflammatory hyperpigmentation.

To prevent hyperpigmentation, or to stop it becoming more prominent:
Avoid exposure to the sun. Use a sunscreen with an SPF of 30 or higher to protect the skin and stop hyperpigmentation from becoming darker.
Avoid picking at the skin. To prevent hyperpigmentation from forming after an injury, avoid picking at spots, scabs, and acne.

People can try the following treatments to lighten dark patches of skin and remove hyperpigmentation:
Many people use topical treatments to treat hyperpigmentation.

Topical treatments will include ingredients that lighten the skin, such as:

azelaic acid
hydroquinone
kojic acid
retinoids
vitamin C                                                                                                                                                                                                                                        niacinamide                                                                                                                                                                                                                                            glycolic acid                                                                                                                                                                                                                                            herbal lighteners

Some cosmetic procedures can also lighten areas of skin to reduce the appearance of hyperpigmentation.
Cosmetic procedures for hyperpigmentation include:

laser therapy
intense pulsed light
chemical peels
microdermabrasion

People who are considering undergoing one of these procedures should discuss the process and possible side effects with a skincare specialist.