How does SR work gain / loss work?

[Kaedi-11739]

Here is the full textbook on skill rating:

How Competitive Matchmaking and Rating Works (Season 22)

The rating and matchmaking system is confusing, and a good overview does not appear to be available. The official overview1 is incomplete and does not answer a number of common player questions and concerns. This information below is gathered from sporadic developer posts and videos, salted with my own experience and experiments, various forum threads, and watching streams. Note that since Blizzard does not give exact algorithms, I do have to fill in some gaps, or leave some items unknown. Final…