Scoville Heat Units (SHU) measure the spiciness or heat of chili peppers and other spicy foods. Developed by pharmacist Wilbur Scoville in 1912, this scale quantifies the concentration of capsaicin, the chemical responsible for the heat sensation. The higher the SHU, the hotter the pepper. For example, a bell pepper has 0 SHU, while a jalapeño can range from 2,500 to 8,000 SHU. To determine SHU, a solution of the pepper is diluted in sugar water until the heat is no longer detectable to a panel of tasters. This method, known as the Scoville Organoleptic Test, has been largely replaced by more precise laboratory techniques, but the Scoville scale remains popular for its simplicity and historical significance.