Differentials are a mathematical concept used to describe how a function changes as its input changes. They represent the rate of change or the slope of a function at a specific point. In calculus, the differential of a function gives insight into how small changes in the input lead to changes in the output, helping to understand the behavior of functions. In practical applications, differentials are used in various fields, including physics and engineering, to model real-world phenomena. For example, they can help calculate the speed of an object or the rate of growth of a population. Understanding differentials is essential for solving problems involving change and motion.