Engineers and Physicists - Explain Smoothed Particle Hydrodynamcis (SPH) Particle Method

SPH is a meshless Lagrangian method for solving fluid flows. Originally designed for astrophysics applications, it has additionally been implemented as a method to solve solid mechanics problems where it tends to yield superior results to the finite-element method in applications involving significant deformation and complex geometries.

I need to understand the mechanisms of this method a little better but I'm getting tripped up reading about it. Can some anons explain this a little? How do kernel smoothing functions work? What exactly is a kernel? What is a smoothing length?