Spicy foods taste spicy because they contain certain chemicals that activate sensory receptors in the mouth and cause a sensation of heat. These chemicals, called capsaicinoids, are found in plants belonging to the Capsicum family, which includes chili peppers. When we eat spicy foods, the capsaicinoids bind to receptors on our tongue and mouth, triggering a response from the nervous system that makes us feel the sensation of heat. This response is actually a form of pain, which is why spicy foods can sometimes be uncomfortable to eat.