Kiyoshi Itô was a prominent Japanese mathematician known for his contributions to stochastic calculus. Born in 1915, he developed the Itô calculus, which is essential for modeling random processes and has applications in various fields, including finance and physics. His work laid the foundation for understanding how to analyze systems influenced by randomness. Itô's most notable achievement is the Itô integral, which allows mathematicians to integrate functions with respect to stochastic processes. This innovation has significantly impacted the field of probability theory and has been instrumental in the development of modern financial mathematics, particularly in the pricing of derivatives.