A hookah is a water pipe that is designed to be used for smoking shisha tobacco. Shisha tobacco is a form of flavored pipe tobacco that is blended with honey or molasses, glycerin, and flavoring that, when smoked out of a hookah pipe, create thick clouds of smoke that are very flavorful. The smoke itself is generated at the top of the hookah bowl, passes down through the hookah stem into the base where it is filtered through the water, and then passes back up through the hose that you are inhaling on.
While shisha tobacco is the most common substance smoked in a hookah, other substances can also be smoked, including herbal shisha, marijuana, and weed. However, it is important to note that hookah smoking exposes you to nicotine and toxic chemicals, just like other forms of tobacco smoking.