Milia are a collection of small white spots commonly known as milk spots. Though common among young babies, they can occur in adults and become permanent. While they aren't a medical risk, many people with milia would prefer to remove them, which is possible with clinic treatment.
Because they are traditionally associated with babies (and usually fade away within a few weeks of birth), milia can cause confusion with adults. They are often mistaken for whiteheads, which can cause ill-advised attempts to scratch or squeeze them.
In fact milia are tiny cysts that are located immediately below the epidermis, the very outer layer of skin, making their distinctive colouring so visible. The white comes from an excess build-up of keratin, which is natural part of the skin, also found in nails and hair.