Basic info about Avatars / skeleton


Hi all
I’m researching about HiFi for potentially using it for a project of mine.
I’m looking for information about avatars and skeletons. Is the HF avatar based on a template skeleton? First step for me is to create unique and special animations and learn how to control them via keyboard input.
I guess I need a kickstart to understand how HF works. I might not have found all the info available, if there are pdfs, or wiki pages about this please link me to them.