What are Erlang processes behind the scenes?

Question

I've got very limited knowledge about Erlang, but as far as I understand, it can spawn "processes" with a very low cost.

So I wonder, what are those "processes" behind the scenes?

Are they Fibers? Threads? Continuations?

Answer 1

They are Lightweight Processes.

Also see my question Technically why is processes in Erlang more efficient than OS threads.