“Well-Known is a free, open index of well-known resources. It scans millions of domains at regular intervals, compiling a searchable database of structured well-known resource data. The search engine supports specific search filters for each resource type, enabling detailed queries to answer a wide variety of questions. 10 resources are currently supported. Well-known resources are files hosted by sites at specific “well known” locations. These resources are used to communicate a variety of information about the site and the services it provides to developers, other sites and services, etc. Resource formats and locations are usually defined in specifications, though some have arisen from loose consensus without being formally specified. They are often located under the /.well-known/ path. You can read more about well-known resources here.”