Moisturizer should be used twice daily - in the morning and evening. In the mornings, it helps to provide skin with a hydrated base before applying makeup or sunscreen. At night, it helps keep skin hydrated while you sleep and can also help protect against environmental stressors such as pollution or dry air. Moisturizer also helps to create a protective barrier on the skin, locking in any active ingredients from serums or other treatments that were applied beforehand. This will enhance the effectiveness of any skincare products you use.