Time-based One-time Password Algorithm

The  Time-based One-time Password Algorithm  (TOTP) is a mechanism of generating a one-time password from a shared secret key and the current time, often used for two-factor authentication.

One Time Password
(stub, could be expanded into its own page, one time password, and redirects fixed accordingly)

The more general concept of a one time password can be generated in other ways, and is sometimes communicated via email.

Services that Support TOTP

 * GitHub - GitHub uses TOTP for two-factor auth when signing in
 * Google - Google uses TOTP for two-factor auth when signing in
 * indieauth.com - indieauth.com used to support TOTP as a login mechanism