The tool queries RDAP (Registration Data Access Protocol), the modern, structured replacement for WHOIS that registries publish over HTTPS in machine-readable JSON. It reads the creation event for the domain and calculates the elapsed time to today, so the age is based on the official registry record rather than a guess or a scraped page. Because RDAP returns clean, typed fields instead of the free-form text old WHOIS used, the dates and registrar names it reports are far more consistent across providers.
From a single lookup the tool surfaces the registrable domain, the registration (creation) date, the age expressed both in whole years and in total days, the expiry date, the most recent update date, the registrar, and any domain status codes such as clientTransferProhibited. Each of those comes straight from the registry response.