Hermann Riemann was a German mathematician born on September 17, 1826, known for his contributions to various fields, including analysis, differential geometry, and number theory. He is best recognized for the Riemann Hypothesis, a conjecture about the distribution of prime numbers that remains one of the most important unsolved problems in mathematics. Riemann's work laid the foundation for many modern mathematical concepts. His introduction of Riemann surfaces revolutionized complex analysis, while his ideas in Riemannian geometry significantly influenced the development of general relativity by Albert Einstein. Riemann passed away on July 20, 1866, but his legacy endures in mathematics and physics.