Nikolai Chebyshev was a Russian mathematician born in 1821, known for his significant contributions to various fields, including number theory and approximation theory. He developed the Chebyshev polynomials, which are used in numerical analysis and have applications in engineering and computer science. Chebyshev also made advancements in probability and statistics, particularly through his work on the Chebyshev inequality, which provides a way to estimate the probability of a random variable deviating from its mean. His influence extends to modern mathematics, where his ideas continue to be relevant in various scientific disciplines.