ETH.Radio is ETHDNS for the .eth domain. Because .eth is not a registered DNS top-level domain it is normally inaccessible from DNS, but by appending .radio to the domain the relevant information cam be obtained. For example, a DNS A record request for mydomain.eth.radio would look up the A records in ENS for mydomain.eth.
ETH.Radio is a alternative to ETH.Link released by Meson Network. ETH.Radio allows users and dApp developers to effortlessly access and host static sites built with a combination of IPFS and ENS.
Please use the #🧐dev-suggestions channel in our Discord server for any questions.