The Scoville Heat Unit Scale (SHU)  is a measurement system used to quantify the heat or spiciness of peppers and other foods, based on their capsaicin content. Capsaicin is the chemical compound responsible for the burning sensation you feel when eating spicy foods.

The scale was developed by Wilbur Scoville in 1912, and it measures the heat of peppers in Scoville Heat Units (SHU). The higher the number of SHUs, the hotter the pepper. Carolina Reaper, one of the hottest peppers in the world, has an average of around 1.5 million SHU, and some can even go over 2 million SHU.

The heat level is determined by diluting the pepper extract in sugar water until the heat is no longer detectable to a panel of tasters. The more dilution it takes, the higher the Scoville rating.

This scale is widely used to describe the spiciness of peppers, hot sauces, and other spicy foods.