A mug is a sturdily built type of cup often used for drinking hot beverages, such as coffee, tea, or hot chocolate. But many people also drink beer from mugs also. The beer stein was derived from mugs, only a stein had a lid on the top. One of the reasons mugs are so popular is because of their handle. When hot drinks are served, the handle provides adequate protection from the heat of the liquid. When drinking beer, the handle provides an easy way to carry your cup around with you. Mugs come in several styles and sizes.