Registering a domain name is a three-party transaction: a registry operates the extension (.com, .co.uk), an ICANN-accredited registrar sells registrations in it, and you become the registrant of record for a term of one to ten years. Nothing is bought outright: a registration is a renewable right to the name, and every promise a registrar makes sits on top of that simple structure. This page walks the structure, the checks and the traps.
The three parties, and which one you are dealing with
The registry runs the authoritative database for the extension and never sells to the public. The registrar is your counterparty: it files the registration with the registry, bills you, and holds the controls for your record. You are the registrant, and the registrant field of the record, not the payer of the invoice, is who owns the name. Register through an agency or a developer and insist the registrant is you: unwinding a name held in a contractor's account is the single most common domain dispute a small business meets.
What to check before you pay a registrar
Four things decide whether a registrar is safe to use, and none of them is the headline price. First, the renewal price: promotional first years commonly renew at a multiple, and the renewal column is the price you will actually live with. Second, transfer policy: taking a name elsewhere needs an unlock and an authorization code, and a registrar that buries either is a warning. Third, whether WHOIS/RDAP privacy is included or an upsell. Fourth, DNS control: you want to point the name at any host, not only the registrar's own.
The record itself: what a registration contains
A registration carries the registrant, admin and technical contacts, the nameservers, the expiry date and the status codes (clientTransferProhibited means the transfer lock is on). RDAP, the successor to WHOIS, is the public read of that record: look any name up at ICANN's RDAP service before buying it second-hand, and look up your own after registering to confirm the registrant is you. Expiry is the failure mode that kills businesses: set the name to auto-renew, keep the payment card current, and calendar the date anyway.
Domain first or hosting first
The domain and the hosting are separable purchases, and keeping them separable is worth something: a name registered with one company and hosted at another can change either side without touching the other. Registrars bundle hosting and hosts bundle registration because each wants both relationships. Neither bundle is wrong, but read each half's renewal terms on its own, and make sure the nameservers are yours to change. The service page this answer feeds works through the combined decision.
Questions people ask about domain registration
Can I buy a domain name permanently?
No. Registrations run one to ten years and renew. What you own permanently is the right to keep renewing while you hold the registration and the extension's rules allow it.
What happens the day a domain registration expires?
Most extensions give a grace window where the registrant can renew at the normal price, then a redemption period at a much higher fee, then public release. Auto-renew with a working card avoids the whole ladder.
Is the domain name I want gone forever if it is taken?
Not necessarily: RDAP shows its expiry and registrar. It may lapse, the holder may sell, and close variants or another extension are often the faster answer.
Does registering a domain include a website?
No. Registration gives you the name and control of its DNS. A site needs hosting, which is a separate service the name points at.