.well-known

 .well-known  is literally the path "/.well-known/" under a domain and used as a standardized (literally a "well-known") location for discovering domain-wide meta-data, and is generally avoided by IndieWeb-related specs, instead preferring follow your nose discovery techniques and methods.

It has been codified by the IETF and IANA in RFC5785 and registry of Well-Known URIs respectively.

Relevant Uses

 * Let's Encrypt for proof of domain ownership
 * WebFinger for discovery of user data (e.g. used by Mastodon)
 * Dat for linking domains to lookup keys on the dat network
 * to specify a Do Not Track policy: https://www.eff.org/de/deeplinks/2017/10/do-not-track-implementation-guide-launched
 * Thunderbird e-mail client autoconfiguration: ,
 * W3C Editor's Draft: A Well-Known URL for Changing Passwords