In case anyone from Circle CI reads here:
I haven't had the need for a hosted CI so far so this is all new to me. I looked at the Circle CI homepage and they have a video on the homepage "See how Circle CI works". Try watching that without sound. It's useless. I'm not sure why anyone would create a video like that.
This is another homepage that already assumes that everyone knows what it does and is no help to people unfamiliar with it.