Dark neck is a common skin problem, which can be caused by sunburn, dirt, dead skin, rubbing of tight clothes, pollution and lack of proper skin care. In some cases, hormonal changes, obesity or insulin resistance can also be the cause.
Home remedies include baking soda scrub, lemon-sugar scrub, aloe vera gel, turmeric-milk pack and tomato-honey pack. But if the problem persists for a long time, consult a dermatologist.