Cookies may be used by this site to track user flows across the site with the goal of improving the quality of the service provided. (No such cookies exist today, but they may be added at a future time.)
All content on this site is provided free of charge without restriction. Login is not required. Login is supported (via Google identity management) as a service to users to remember their progress through content on this site. If you do not wish the site to record such details, please do not login.
If you log on, then this is assumed to be permission for the site to remember details about your usage. This is stored in a database with a Google allocated internal ID (not your email address) along with progress details. These details will never be shared with other parties.