Permissions schemes Google uses

gistfile1.txt

Federated login using 3rd party providers (LDAP)
Sign-in-as-a-Service
Concurrent logins with multiple accounts
Forced logins with single accounts (Drive)
API keys that use Oauth2
API keys that use don't use Oauth2
IP-restricted API keys
Domain-restricted API keys
Alternate accounts (password reset)
Account forwarding (email)
Shared access to Google users
Shared access to non-Google users
Shared access that requires non-Google users to become Google users
Shared access to the public
Shared access to Circles
Family accounts
Application-level permissions
Shared access (development accounts)
Anonymous accounts (spreadsheets)