login

 login  (AKA sign-in ) is a feature of many websites where a user is asked to provide a username (often an email address) and password in order to gain (more) access to the site; the IndieWebCamp wiki uses IndieLogin for delegated sign-in; other sites or services directly use IndieAuth for delegated sign-in.

Delegated Sign-in
(stub, consider making a separate page if this grows too big)

Delegated sign-in is a growing method for websites to allow signing-in via a third party authentication provider, instead of every website asking users to create a new username & password (and submit their email address).

Delegated Sign-in Standards
There are several standardized delegated sign-in protocols
 * IndieAuth
 * RelMeAuth

Obsolete (per https://openid.net/developers/specs/)
 * OpenID 1.x, 2.0

Delegated Sign-in Services
There are services that implement one or more delegated sign-in protocols
 * IndieLogin is a delegated sign-in provider that supports IndieAuth, OpenID, and RelMeAuth with a specific set of OAuth supporting external services such as GitHub and Twitter.

Proprietary Delegated Sign-in
There are several popular proprietary delegated sign-in services that are often displayed together on a website using delegated sign-in:

 Screenshot from the article The Decline of OpenID.

Examples from the above screenshot:
 * Sign in with Google
 * Sign in with Facebook
 * Sign in with Twitter
 * Sign in with Github

Displaying such a variety of brands/logos/appearances is also known as the NASCAR problem.

The following from the screen shot are not examples of delegated sign-in:
 * Sign in with email — not delegated, this typically depends on an email-based service-specific account and password, though some services may use a one-time emailed authorization link.
 * Sign in with phone — also not delegated, this typically depends on a one-time code sent via SMS to a mobile phone

Silo Examples
Typepad's login form includes options for Facebook, Twitter, MySpace, Yahoo, AOL/AIM, Blogger, LiveJournal, and Wordpress.com as of 2019-11-08. Notably, Myspace and AIM no longer exist.