Partial derivatives are a concept in calculus that extends the idea of derivatives to functions of multiple variables. When dealing with functions of more than one variable, a partial derivative measures how the function changes concerning one specific variable while holding the other variables constant.

If f(x, y) is a function of two variables x and y, then the partial derivative of f with respect to x, denoted as ∂f/∂x, represents how f changes with respect to x while treating y as a constant. Similarly, the partial derivative with respect to y, denoted as ∂f/∂y, measures the change in f with respect to y while treating x as a constant.

Mathematically, the partial derivatives are defined as follows:

Partial Derivative with respect to x: ∂f/∂x = lim (Δx → 0) [f(x + Δx, y) - f(x, y)] / Δx

Partial Derivative with respect to y: ∂f/∂y = lim (Δy → 0) [f(x, y + Δy) - f(x, y)] / Δy

For functions of more than two variables, the concept of partial derivatives extends similarly. Each partial derivative provides information about the rate of change of the function concerning a specific variable while holding the other variables constant.

Partial derivatives are crucial in fields such as physics, engineering, economics, and optimization problems where functions depend on multiple variables. They allow us to analyze how a function changes with respect to each individual variable.