Steam - sh.itjust.works

Their engine is called source.

The collection of libraries valve release to use steam (the piping, if you will), is called steamworks.

That’s not why it’s called that. The real reason is that they didn’t bother ever giving it a name. When they needed a stable fork so they could further develop the engine without interfering with the development of Half-Life, they referred to the two source codes “GoldSrc” and “Src” and the name stuck.