Riemann refers to Bernhard Riemann, a 19th-century German mathematician known for his contributions to analysis, differential geometry, and number theory. He is best known for the Riemann Hypothesis, a conjecture about the distribution of prime numbers, which remains one of the most important unsolved problems in mathematics. Riemann's work laid the foundation for many modern mathematical concepts, including Riemann surfaces and Riemannian geometry. His ideas have influenced various fields, such as physics and engineering, particularly in the study of complex functions and the geometry of curved spaces.