Substance Designer is a Node-Based editor. That means almost every type of project or resource will involve placing nodes (building blocks) and connecting them to create a chain of operations (a Graph).This page explains the concept of Node-Based workflows, and provides a summary of the 3 main types of Graph you can author in Substance Designer.
Working in Substance Designer is different from other 2D image editing software such as Photoshop. Instead of performing an action manually (like adjusting saturation by going to a menu option and changing a slider), you construct the logical steps of editing or creating your image. This happens by building a network of little building blocks, called "Nodes". Image data travels from left to right through the building blocks, connected by Links that determine the path of the information. Every Node, if connected, will contribute to the final results.
The major advantage is that your workflow becomes non-linear. Unlike actions performed manually that go into a history stack, you can always swap out or modify a Node at any point in time. If you decide that your very first Contrast adjustment, affecting the result of your image all the way to the end, was too much, then you can still go back and adjust it or even cut it out completely, without losing all the work you performed afterwards.
Sub-Graphing is a key process in Substance Designer. It allows you to build your own nodes by taking any size or type of Graph and packaging it up as new Node building block. These types of Nodes are called "Graph Instances" This allows you to be much more efficient, save time and share work with others. You developed a great technique for edge wear for example? Sub-Graph it and re-use it yourself, share it with the community, or your team!
For more information about Sub-Graphs, there is a dedicated section about them in the documentation.
Any Node in your chain of operations will have some form of control: buttons, sliders, settings for you to tweak, influencing the final result. If you create a Sub-Graph, or want to export your Substance File to another application, you can build your own "control panel" for your files, allowing anybody using the Graph to tweak and modify it with a fully unique control panel, exposing endless possiblities.
Below you can find a summary of the three types of Graph you can edit in Substance Designer, as well as a link to the relevant section of the documentation.