Bernard Riemann is one of those figures you can’t be a mathematics major without learning about. His name attaches to an enormous amount of analysis. One Riemann-named thing every mathematician learns very well is the Riemann Sum. It’s the first analysis model we use to explain why integration works. And we can put together a version of this for numerical integration. Its greatest use, though, is that we can use it to justify other ways to integrate that are easier to actually use. Great little utility.