On April 23, 1882, German mathematician and physicist Emmy Noether was born, who is best known for her groundbreaking contributions to abstract algebra and theoretical physics. Albert Einstein called her the most important woman in the history of mathematics, as she revolutionized the theories of rings, fields, and algebras.
On August 8, 1900 German mathematician David Hilbert gave a speech at the Paris conference of the International Congress of Mathematicians, at the Sorbonne, where he presented 10 mathematical Problems (out of a list of 23) all unsolved at the time, and several of them were very influential for 20th century mathematics.