Mathematics underpins much of science and technology currently. The most ancient disciplines are arithmetic, algebra, geometry and analysis. Topology, the investigation of properties conserved under continuous deformations, is more recent. It was established on solid ground by Henri Poincaré in his ground-breaking 1895 paper “Analysis Situs”, in which he introduced the new concepts of homotopy, fundamental groups, and homology, which are now part of algebraic topology. Initially, algebraic topology dealt with the properties of spaces that are preserved under continuous deformations, such as stretching, crumpling, and bending, but not tearing or gluing. Algebraic geometry deals with the solutions to polynomial equations, with the corresponding algebraic varieties and cohomology.