Rating Systems attempt to assign a numeric measure to a player's strength based upon the player's results in games against other players. There are a number of rating systems in use across the globe. Some ratings systems are limited to particular countries or organizations others span either a continent or the entire globe via Internet play.
- French Ladder which is essentially GoR with parameters retuned
- Glicko Rating
- GoR used by the European Go Federation (EGF)
- Korean Professional
- Sonas by Jeff Sonas? of ChessMetrics
- TruSkill: A Bayesian skill rating system
- Whole History Rating a modern rating system claiming to have the highest accuracy for rating players whose playing strength changes over time.
- Russian (text in Russian)
- Rating Histogram Comparisons Graphs and some theory, comparing AGA, EGD, KGS and, for reference USCF (chess)
- Rank Worldwide Comparison Tables of equivalent strengths in 5 amateur and 7 go server rating systems
- /DataCollection Our data on which these tables are based
- Discussion pages:
- Personal musings (with some discussion)
- Holigor's Rating Of Go Players Ratings by HolIgor and some ideas (not updated between 2004 and 2022-01-01)
- Migeru's musings on go ratings Comments by Migeru on weaknesses in ELO-based rating systems such as the EGD
- Internet Ratings Database A proposal by Stormer for a unified ratings database for information exchange between Go servers
- How to align rating systems A proposal by Reflame for how to harmonise the various rating systems
- Point ranking schemes, used to set handicap and komi in clubs or small groups
- Other resources:
- https://www.goratings.org/en/ Up-to-date ELO ratings for professional players globally, maintained by Rémi Coulom
-  A Japanese rating page which no-one has described in any detail here (as of 2022-01-01)
- EGF Rating per Rank Brief notes on conversions between EGD ratings and tradtional ranks, with some statistics
- Rating Theory Homepage As of 2022-01-01 this seems to have been hijacked by blockchain spammers (perhaps it is archived)
 http://kashi.dip.jp/~kashi/rating/rating.pdf seems to comprise interesting content w.r.t. ELO (I guess, tderz). As it is written in Japanese (which I cannot read beyond some Igo-terminology) s.o. else might comment more on it.
Some figures resemble derivative pricing model graphs near expiration, where volatility goes up and normal Black & Scholes do not hold anymore.
With Go that would be slightly different: near same strengths encounters give very predictable results,
high strength difference encounters bear high uncertainty/volatility/deviation.