Answer
Calculus of Variations, a branch of mathematics, owes its development to Carathéodory's contributions. This field explores the optimization of functionals, which are functions of other functions. Carathéodory's work laid the foundation for understanding the necessary conditions for extrema in variational problems, known as the Euler-Lagrange equations. His contributions have had a profound impact on fields such as mechanics, physics, and engineering, where optimization plays a crucial role.