Compound is the most common resource in Astroneer, alongside with Resin and Organic. It can be obtained by trading resources on the Trade Platform, through mineral extraction or by mining it from deposits on Planets. It was also obtainable from compound Nodes, which were removed, along with all the other nodes, in version 0.4.10221.0.
This resource is used frequently in crafting Modules, in the Printer, in the Vehicle Bay and in the Backpack Printer.
Post-Research Update Compound (note on it's light blue recolor)
Regenerating Compound Node. These were removed as of 0.4.10221.0.