FEM is super important/useful in engineering and scientific disciplines. While the basic concepts are quite straight forward, all the details you need for deve

FEM is super important/useful in engineering and scientific disciplines. While the basic concepts are quite straight forward, all the details you need for developing useful engineering FEM tools make it really challenging. You can read a textbook and learn a lot, but in production tools you have to figure out how to handle things like: mesh generation, mesh adaptivity, coupled nonlinear equation support, different time-stepping/integration schemes, 3D, convective term stabilization, sparse matrix solvers, preconditioning, parallelization (e.g. MPI for supercomputers), and much much more. I work on an open source FEM framework called MOOSE (https://mooseframework.org/ https://mooseframework.org/) and get to enjoy digging in this stuff every day!