What characteristic best describes a facial steamer?

A facial steamer is best characterized by its ability to produce a stream of warm steam. This warm steam is beneficial for the skin as it helps to open up the pores, making it easier to cleanse and exfoliate. The heat from the steam can also increase circulation, improving the overall appearance and health of the skin by promoting hydration and loosening impurities.

The other choices describe actions or characteristics that do not accurately reflect the function of a facial steamer. For example, cool mist does not provide the therapeutic effects that warm steam does, and drying the skin is contrary to the moisturizing benefits that steam treatment offers. Similarly, applying cold compresses is not related to the function of a steamer, which focuses on warmth and hydration rather than cold treatment. Thus, the defining characteristic of a facial steamer is its production of warm steam, which plays a crucial role in skincare routines.