Stovetop espresso makers are a long Italian tradition. The lower chamber is filled with water, ground coffee is added to the filter, and the espresso maker is put on a heat source. The developing steam pushes through the coffe into the upper chamber. Espresso is served! These little machines are perfect for the occasinal espresso drinker or to take on vacation. Bialetti even invented the fist ever cappuccino maker, where milk is filled into the upper chamber, steamed by the boiling water and mixed with the coffee. Can be used on any heat source.