Anything about games running on multiple platforms will go here. That may end up being a bit too narrow but will start with JavaScript and Godot games. Maybe consoles someday.
There's a bit of controversy about this term, but we'll go with it here and you'll find anything related to building websites without always relying on a server generating content at request time.
Maybe this topic is a bit broad, so it could include things related to backend, frontend, games, Arduino, FaaS/Serverless, build systems, general scripting, and beyond.
Various projects are included here related to things like Arduino, Bluetooth controllers, building Quadcopters, and even repairing headphones.