Amazon isn’t exactly the most stylish place to shop for clothes. Most of its top-selling women’s fashion items are simple pieces: easy dresses, spandex workout gear, socks, and underwear—a lot of it from brands you’ve probably never heard of. But that doesn’t mean Amazon isn’t a powerhouse for apparel sales. As traditional department stores have declined, Amazon has become one of the most popular clothing retailers in the US, especially among millennials.