Partial fraction decomposition is a technique used in algebra and calculus to break down a complex rational expression into simpler fractions. This process involves expressing a rational function, which is a fraction where both the numerator and denominator are polynomials, as a sum of simpler fractions with simpler denominators. By breaking down a complex rational expression into these simpler components, it becomes easier to integrate, differentiate, or analyze the function. This chapter is dedicated to partial fraction decomposition.