Dark spots can appear as a result of acne, sun damage, or a rash, which is also known as post-inflammatory hyperpigmentation. They can can also occur when dealing with hormonal melasma. No matter the cause, it takes a special cocktail of brightening ingredients to lighten them up. That's where dark spot correctors come in.  You'll most likely find hydroquinone or vitamin C, which is known for its brightening properties, in most dark spot correctors.