Reserved Test TLDs
Reserved test TLDs are [[tld|top-level domains]] set aside by [[iana|IANA]] (RFC 2606) for documentation, testing, and development purposes that will never be delegated in the public [[dns|DNS]] root zone. The four primary reserved TLDs are .test (for software testing), .example (for documentation and illustration), .invalid (guaranteed not to resolve), and .localhost (for local machine loopback). Using these TLDs in code, documentation, or demos ensures that examples never accidentally resolve to real domains or create unintended internet traffic.
Example
RFC documentation uses example.com, example.net, and example.org for all illustrative purposes; developers use http://myapp.test during local development to avoid conflicts with live domains.