Glossary
What is Class G airspace?
Uncontrolled airspace, in which air traffic control provides no separation service to anybody. It sits underneath Class E, usually as a layer near the surface away from airports with instrument approaches. Cloud and visibility minimums still apply, and they vary with altitude and with day or night.
Also called Uncontrolled airspace
That is the whole entry for now. The longer version, with the mechanics and worked examples, is still to be written. See autorotation for how those read once they exist.