--- id: "domain-name" kind: "glossary-term" title: "domain name" language: "en" category: "DNS and technical foundations" updated: "2026-10-10T10:28:55Z" canonical: "https://tldlog.com/glossary/domain-name/" translations: es: "https://tldlog.com/es/glosario/nombre-dominio/" de: "https://tldlog.com/de/glossar/domainname/" fr: "https://tldlog.com/fr/glossaire/nom-domaine/" it: "https://tldlog.com/it/glossario/nome-dominio/" pt-BR: "https://tldlog.com/pt/glossario/nome-dominio/" ru: "https://tldlog.com/ru/glossariy/domennoe-imya/" zh-Hans: "https://tldlog.com/zh/cihui/yuming/" --- # domain name A name made of labels separated by dots, such as example.org, that points to a place on the internet. The part at the far right is the top-level domain. People usually register the label just to its left through a registrar, for a set number of years. A domain name is the readable name, such as example.com, that people type to reach a website or that appears after the at sign in an email address. It is easier to remember than the numeric address of a computer, and it can stay the same when the server behind it changes. ## What a domain name is, in plain words The DNS works like the internet's directory: you give it a name, and it returns the information stored for that name, such as the address of a web server or the servers that receive its mail. Technically, a domain name is an ordered list of labels: the pieces of text between the dots. The word is used loosely, as the IETF's own terminology document notes. Engineers call any name in the DNS a domain name, including shop.example.com. In the domain industry, "a domain" usually means the name someone registered, such as example.com. ## How a domain name is built: labels, levels and the dots A domain name is read from right to left, from the most general part to the most specific: 1. The root, the top of the DNS tree. Its label is empty, so it is normally invisible; strictly, it is the final dot of a name. 2. The top-level domain (TLD), such as com or es. To the DNS, a TLD is simply one level below the root. 3. The second-level domain, the label just left of the TLD. 4. The third level and any further levels. In shop.example.com, com is the TLD, example the second level and shop the third. Which level the public registers at is a matter of policy, not technology, and the name itself does not show it; outside sources such as the Public Suffix List record it. Under most TLDs it is the second level, but some country-code TLDs use fixed second-level labels. For Spain, the national plan for .es (Order ITC/1542/2005) allows third-level names under .com.es, .nom.es and .org.es, which are open and assigned without prior checks, and under .gob.es and .edu.es, which are restricted (as of October 2026). In a name under .com.es, es is the TLD, com is a fixed second level, and the registrant chooses the third-level label. ## Which characters are allowed and how long a name can be The DNS protocol itself only limits length. The familiar character rules come from the applications that use names (host names, email and the web) and from each registry's policy. The traditional rule is LDH: the ASCII letters a to z, the digits 0 to 9 and the hyphen, with no hyphen at the start or end of a label. Labels with two hyphens in the third and fourth positions are reserved; those starting with xn-- carry the ASCII form of an IDN, a name with accented letters or a non-Latin script. Capital letters make no difference: Example.COM and example.com are the same name. Each label can be up to 63 bytes. The whole name can be up to 255 bytes in the form the DNS stores, which also counts a length byte for each label and one for the root, so the written name is a little shorter. Registries add their own rules. As of October 2026, .es allows the letters of the Spanish languages, digits and the hyphen; no hyphen first or last; no name starting with xn--; at least three characters at the second level and two at the third; and at most 63. Anyone planning a short or unusual name should check the current rules with the registry or their registrar. ## Subdomains, the apex and the fully qualified name Technically, a name is a subdomain of another when it ends with all of that name's labels: shop.example.com is a subdomain of example.com, which is itself a subdomain of com. In everyday use, a subdomain is a name the holder creates under their registered domain, with no registry or registrar involved; www is one like any other. The apex is the top of a zone, the name with nothing in front of it, such as example.com. The zone's SOA and NS records live there. An FQDN contains every label up to the root and, strictly, ends with the root's dot, as in mail.example.net. with its final dot. In practice the dot is usually left out. It matters where software might otherwise add a local domain to a name. ## What you actually own when you register a name For gTLDs, ICANN's contract with registrars does not speak of an owner. The 2013 RAA defines a "Registered Name" and its "Registered Name Holder", whose rights and duties come from a registration agreement with an ICANN-accredited registrar, within the policies of the registrar, the registry and ICANN. As of October 2026, ICANN's page on registrant responsibilities says the holder must keep contact details accurate and current, answer the registrar within 15 days, keep payment details current if the name renews automatically, and accept sole responsibility for registering and using the name. A registration lasts for a set term and must be renewed. Three roles are involved: the registry decides what goes into the TLD's zone, the registrar acts as the go-between, and the registrant is the person or organization on whose behalf the name is registered. Not every registration goes through a registrar. For ccTLDs, the rules come from each registry or from national law, such as the 2005 Order for .es. Whether a domain name counts as property is a legal question that depends on the country. ## Domain name, URL, website and email address: the differences In a web address, formally a uniform resource locator (URL), the domain name is only the host part; a path such as /news points to a page on that server. An email address has a local part, the at sign and a domain: `editor@example.com` uses example.com. A website is content stored on a server; the domain name points to that server through DNS records. The same domain can serve a website, email, both or neither. A domain hack is a name read across the dot, where the TLD completes a word: a word ending in ly can be split before those letters to use .ly. Domain hacks usually rely on country-code TLDs: as of October 2026, IANA lists .ly as the ccTLD of Libya and .me as that of Montenegro. That country's registry rules still apply. ## Sources - [RFC 1034: Domain Names - Concepts and Facilities](https://www.rfc-editor.org/rfc/rfc1034.txt) - [RFC 9499: DNS Terminology](https://www.rfc-editor.org/rfc/rfc9499.txt) - [Registrants' Benefits and Responsibilities](https://www.icann.org/resources/pages/benefits-2013-09-16-en) - [Orden ITC/1542/2005, de 19 de mayo, por la que se aprueba el Plan Nacional de nombres de dominio de Internet bajo el código de país correspondiente a España («.es»)](https://www.boe.es/buscar/doc.php?id=BOE-A-2005-8902) ## related terms - [TLD](https://tldlog.com/glossary/tld/) - [second-level domain](https://tldlog.com/glossary/second-level-domain/) - [registration](https://tldlog.com/glossary/registration/) - [DNS](https://tldlog.com/glossary/dns/)