I think it was the first language to specifically introduce the async and await keywords, but it wasn't even the first language on the .NET platform to support

I think it was the first language to specifically introduce the async and await keywords, but it wasn't even the first language on the .NET platform to support the programming model - that honor goes to F#. See https://tomasp.net/academic/papers/async/async.pdf https://tomasp.net/academic/papers/async/async.pdf