In mathematics, a "differential" refers to a concept that measures how a function changes as its input changes. It is often represented as "dy" for a small change in the output and "dx" for a small change in the input. The differential helps in understanding the slope of a curve at a specific point, which is essential in calculus. In physics, differentials are used to describe how physical quantities change. For example, in physics, the differential can represent changes in velocity or acceleration over time. This concept is crucial for analyzing motion and understanding the relationships between various physical properties.