According to the Merriam-Webster Dictionary, hookah is defined as a water pipe. The below picture shows a basic example and the parts of a hookah water pipe.
(photo from www.cdc.gov)
Because the smoke enters a water bowl before the user inhales people believe smoking hookah is a safe alternative to smoking traditional cigars or cigarettes and the smoke is "filtered" through the water. When in reality the water only cools the smoke, making it easier to inhale.
Smoking hookah is extremely harmful for the lungs. A World Health Organization report showed that about an hour of smoking hookah is as bad for our health as smoking 5 packs of cigarettes (100 cigarettes). And if that isn't scary enough, we've seen a huge increase in the amount of youth and young adults using hookah.
Studies done in the past years have increasing popularity of hookah, 40% of college students have ever smoked hookah. Hookah appeals to young people in a way that is different from traditional tobacco like cigarettes and cigars.
Tobacco Free Florida shared this great, myth busting infographic on hookah smoking based on a survey done by the University of South Florida.
For more information about hookah check out the links below: