Delta is one of the Greek letters, capitalized as δ and lowercase as δ. In a quadratic equation, change, heating in chemical reaction, diopter and discriminant are expressed. Delta is the pronunciation of the fourth Greek letter, capitalized as δ and lowercase as δ. In mathematics or physics, the capitalized δ is used to represent the incremental symbol. And lowercase δ is usually used to represent variables or symbols in higher mathematics. In mathematics or physics, capitalized δ is a symbol used to represent the amount of change. And lowercase δ is usually used to represent variables or symbols in higher mathematics.