Domain glossary

The technical machinery that makes domain registration and lookup work.

• RDAPRDAP (Registration Data Access Protocol) is the modern HTTPS-based replacement for WHOIS, standardised by IETF in 2015. ICANN required all gTLD registries and registrars to support RDAP by January 2025, when WHOIS for gTLDs was officially sunset. RDAP returns structured JSON, supports authenticated access, and is the canonical way to look up domain registration data today.Registration Data Access Protocol
• WHOISWHOIS is the original protocol for looking up domain registration data, dating to 1982. It runs over TCP port 43 and returns unstructured text. ICANN sunset WHOIS for gTLDs on January 28, 2025 in favour of RDAP, though most registrars still provide it for backward compatibility. Country-code TLDs largely retain WHOIS as their primary lookup.
• DNSDNS (Domain Name System) is the global infrastructure that translates human-readable domain names into IP addresses. It is what allows browsers to find example.com when you type it. DNS operates as a hierarchical, distributed database with root servers at the top, TLD servers underneath, and authoritative nameservers for individual domains at the bottom.Domain Name System
• EPPEPP (Extensible Provisioning Protocol) is the standard protocol that registrars use to communicate with registries. It defines how to register, renew, transfer, update, and delete domains. EPP is XML-based, runs over TCP with TLS, and is specified in RFC 5730 (and extensions). The EPP "status codes" you see in WHOIS (clientHold, pendingDelete, etc.) are part of the EPP specification.Extensible Provisioning Protocol
• DNSSECDNSSEC (DNS Security Extensions) is a set of cryptographic extensions to DNS that protect against forgery and cache poisoning. It works by signing DNS records with a chain of trust from the root zone down to the domain. DNSSEC is optional — domain owners can enable it at their registrar, and resolvers can validate signatures to detect tampered responses.DNS Security Extensions

Who does what in the domain ecosystem — registrants, registrars, registries, and ICANN.

• RegistrarA registrar is an ICANN-accredited (for gTLDs) or registry-accredited (for ccTLDs) company that sells domain registrations to end-users. Registrars sit between the end-user (the registrant) and the registry (which operates the TLD). Examples: GoDaddy, Namecheap, Cloudflare, Porkbun, Dynadot.
• RegistryA registry is the organisation that operates a top-level domain. Verisign operates .com and .net. Identity Digital operates many gTLDs. Public Interest Registry operates .org. Each ccTLD is operated by a national registry (DENIC for .de, Nominet for .uk, AFNIC for .fr). Registries set policies, run the technical infrastructure, and wholesale to registrars.
• RegistrantThe registrant is the legal holder of a domain registration — the entity (person or organisation) named in the registration record as having the right to use the domain. Registrants do not "own" domains in the property-law sense; they hold a renewable license. The registrant is identified in WHOIS/RDAP records (though usually with PII redacted post-GDPR).Domain owner · Holder
• ICANNICANN (Internet Corporation for Assigned Names and Numbers) is the nonprofit that coordinates global domain name and IP address allocation. It accredits gTLD registrars, contracts with gTLD registries, sets policy for gTLD lifecycle and transfer rules, and operates the IANA function. ICANN does not manage ccTLDs directly — those are operated by national registries with their own policies.Internet Corporation for Assigned Names and Numbers

Lifecycle phases, fees, and ideas you encounter when watching or owning domains.

• NameserverA nameserver (NS) is a DNS server that provides authoritative answers for a domain. Each domain typically has 2-4 nameservers; the registry stores them in the TLD zone, and they are visible in WHOIS/RDAP records. Changing nameservers transfers DNS hosting to a new provider — the most common reason to update them.DNS server · NS
• Expiration dateThe expiration date is when a domain registration ends if not renewed. It is set by the registry and visible in WHOIS/RDAP. After expiration the domain enters autoRenewPeriod, then redemptionPeriod, then pendingDelete — totaling about 80 days for gTLDs before the domain becomes available for re-registration. The registrant can renew at any point in the first ~75 days.Expiry date
• Redemption feeThe redemption fee is what a registrar charges to recover a domain that has entered redemptionPeriod (typically 30 days after auto-renew grace ends). It is set by the registrar, not the registry, and varies widely: $80 at GoDaddy, $189 at Namecheap, up to $300+ for premium gTLDs and some ccTLDs. The fee is in addition to a year of standard renewal.Restoration fee
• Expired domainAn expired domain is one whose registration period has ended without renewal. Expired domains progress through autoRenewPeriod, redemptionPeriod, and pendingDelete before becoming available for re-registration — typically 80 days from expiration for gTLDs. The expired-domain market refers to the broader practice of identifying, watching, and acquiring these names.
• Premium domainA premium domain is a name flagged by the registry as higher-value and priced above standard registration rates. Common premium tiers include 1-3 character names, dictionary words, common surnames, and high-search-volume terms. Premium domains have non-standard pricing: registration may be $100-$50,000+, and renewals often track the premium tier rather than dropping to standard rates.
• AuthcodeAn authcode (also called EPP code or transfer code) is a domain-specific password used to authorise a transfer between registrars. The losing registrar generates the code; the registrant supplies it to the gaining registrar; the gaining registrar uses it to initiate the transfer. Authcodes are required for almost all gTLD and many ccTLD transfers.Auth code · EPP code · Transfer code
• Reserved domainA reserved domain is a name a registry or ICANN has withheld from registration — no registrar can sell it at a listed price. Like premium names, reserved names hold no registry record, so availability tools routinely report them as available when they cannot be registered.Registry reserved name · Blocked domain · Restricted name

What domain investors actually do — drop-catching, sniping, backorders.

• Drop catchingDrop catching is the practice of registering a domain in the moment it becomes available after the previous registrant lets it expire. It is a competitive industry — services like DropCatch, SnapNames, and NameJet operate registrar fleets that submit thousands of registration requests per second when high-value domains drop.Domain catching · Dropping
• Domain backorderA domain backorder is a paid order placed with a drop-catch service before a domain becomes available. The service attempts to register the domain at the moment it drops. If multiple backorders are placed for the same domain, it is auctioned to the highest bidder. Typical price: $59-$80 per attempt with no refund if catch fails.
• SnippingSnipping is informal slang for drop-catching — the practice of registering a domain at the moment it becomes available after the previous registrant lets it expire. The term comes from the auction-sniping practice (placing bids in the final seconds). In the domain context it usually refers to manual or semi-automated catching of low-demand drops, distinct from professional drop-catch services.Sniping

How top-level domains are categorised and what the differences mean for buyers.

• gTLDA gTLD (Generic Top-Level Domain) is a top-level domain that is not associated with a specific country. Examples include .com, .net, .org, .info, .io, .app, and the hundreds of new gTLDs introduced by ICANN since 2013. gTLDs are governed by ICANN policies and follow standardised lifecycle rules.Generic Top-Level Domain
• ccTLDA ccTLD (Country Code Top-Level Domain) is a two-letter top-level domain assigned to a country, territory, or geographic region. Examples: .uk (United Kingdom), .de (Germany), .fr (France), .jp (Japan), .us (United States). ccTLDs are operated by national registries with their own policies — they are not bound by ICANN gTLD lifecycle rules.Country Code Top-Level Domain