Hot on the heels of the Blender 2.91 release, Blender 2.92 is currently in Alpha and one of the most exciting new features is Geometry Nodes. Part of the everything as nodes strategy for future Blender development, the addition of geometry nodes will add procedural capabilities to Blender without requiring programming or scripting. Before the 2.92 alpha, Geometry Nodes were a separate branch with the project page available here.
When using Geometry Nodes, you are can create or modify geometry in your Blender scene using the new Geometry Node Editor. The process is very similar to the current way Shaders and Cycles materials are constructed. The selection of nodes are documented in the manual, however most descriptions are pretty sparse at this point. If you want to get started with nodes you need to run Blender 2.92 or later. Until it is formally released, the best place to get alpha and beta Blender releases is here.
There are two example projects to get you started. The best one currently is this one which shows how to use nodes to scatter rocks across your scene. There is another project that will showcase how to procedurally create a tree, however this project is currently just a place holder.
You can learn more about Blender 2.92 and Geometry Nodes in the video below.