ICANN publishes the complete list of TLD registries and domain name registrars. Registrant information associated with domain names is maintained in an online database accessible with the WHOIS protocol. For most of the 250 country code top-level domains (ccTLDs), the domain registries maintain the WHOIS (Registrant, name servers, expiration dates, etc.) information.
Avoid having numbers in your domain name. People can get confused about whether the numbers is a digit (3) or a word (three). If you want a number in your domain name because there’s a number in your company name, buy both versions (digit and word) and redirect one to the other. Be especially wary about using the number “0” in a domain name as people may see it as the letter “O.”