A _mielle hair masque_ is a type of hair treatment that is applied to the hair after shampooing, but before conditioning; it may even be used as a leave-in conditioner. An example of this treatment would be the Mielle Babassu Oil & Mint Deep Conditioner.
Masques gain their relevance from their specialty ingredients, which render them useful for a variety of hair types and concerns, from protein treatments to hydration. One of the key developments in hair masque history came in the form of professional salon treatments, which charge customers for luxury treatment regimens that employ masques as a key ingredient.