Learn
How domains work, in plain English
For anyone who has looked at .co.uk, "nameservers" or a CNAME record and wondered what it all means. Eight short parts take you from what a domain is to how websites and email find it, about 57 minutes in all. Read them in order, or jump to what you need.
What do you want to do?
- Understand what I actually bought
- Connect my domain to a website
- Set up email on my domain
- Work out what .co.uk, .io or .app means
- Move my domain to another registrar
- Get back a domain that expired
See any domain taken apart
Try
Everything happens in your browser; nothing you type is sent or saved.
https://protocolshop.subdomainexamplename.cosecond level.uktop level/pricingpath
shop.example.co.uk is a subdomain of example.co.uk. Whoever registered example.co.uk can create it for free. Its extension .co.uk has two levels: .uk is the country code and .co is a category under it.
| Registered domain | example.co.uk |
|---|---|
| Subdomain | shop |
| Hostname | shop.example.co.uk |
| Extension | .co.uk |
| Levels | Two-level extension |
| Type | Country code (ccTLD) |
| Run by | Nominet |
The guide
- 1What is a domain name?What a domain name is, the parts it is made of, and how it differs from a URL, a website and a hostname. 7 min.
- 2Subdomains, hostnames and the root domainWhat a subdomain is, why www is one, what the root (apex) domain is, and when to use a subdomain instead of a folder. 5 min.
- 3Domain extensions: gTLD, ccTLD and two-level extensionsEvery kind of domain extension explained: generic, country code, new, sponsored and brand TLDs, and two-level extensions like .co.uk and .com.au. 8 min.
- 4Registry, registrar and registrant: who does whatThe organisations behind every domain: ICANN, IANA, registries, registrars, resellers, you as the registrant, and your DNS, web and email hosts. 6 min.
- 5How a domain becomes a websiteWhat happens between typing a web address and seeing the page: nameservers, DNS lookups, A and CNAME records, web servers and HTTPS certificates. 8 min.
- 6How a domain becomes an email addressHow email finds your domain: MX records, sending and receiving servers, mailboxes vs forwarding, and SPF, DKIM and DMARC in plain English. 8 min.
- 7The protocols behind domains, websites and emailDNS, HTTP, HTTPS and TLS, SMTP, IMAP and POP3, WHOIS and RDAP, EPP and DNSSEC: what each one does, its port and where you meet it. 7 min.
- 8The life of a domain: register, renew, expire, transferRegistration, renewal, expiry, grace and redemption periods, deletion and drops, transfers, auth codes, locks and status codes. 8 min.
The whole thing in one picture
If the words are new, think of a home and its post.
| Domain name | Your street address. Easy to say, and it stays the same when you move things around behind it. |
|---|---|
| Registrar | The agent you lease the address through, and renew it with each year. |
| Registry | The land registry for one kind of address, like every .com. |
| Nameservers | The directory you choose to publish your details in. |
| DNS records | The entries in that directory: where the house is, where post goes. |
| Web host | The house itself, where your website lives. |
| Email host | The post office that receives and keeps your mail. |
| HTTPS certificate | The ID visitors check at the door before coming in. |
Quick answers
The terms people ask about most, in a sentence each.
| Domain name | A name you register for a place on the internet, like example.com. |
|---|---|
| Subdomain | A free name under your domain, like shop.example.com. www is one. |
| Root domain | The domain with nothing in front: example.com. Also called the apex. |
| Extension (TLD) | The ending, like .com or .uk. TLD means top-level domain. |
| gTLD | A generic extension open worldwide, like .com, .org or .app. |
| ccTLD | A two-letter country code extension, like .de, .jp or .uk. |
| Two-level extension | A category under a country code, like .co.uk or .com.au. |
| Registry | The organisation that runs an extension, like Verisign for .com. |
| Registrar | The company you register a domain through and renew with. |
| Registrant | You: the person or business holding the domain. |
| DNS | The internet's directory, turning names into addresses and settings. |
| Nameservers | The servers that hold a domain's DNS records. |
| A and CNAME records | DNS records that point a name at a web server. |
| MX record | The DNS record that says where a domain's email goes. |
| SPF, DKIM, DMARC | DNS records that prove email from your domain is really from you. |
| SSL/TLS certificate | What lets a site use HTTPS and shows it really is that domain. |
| Auth code | The password you give a new registrar to transfer a domain. |
| Redemption period | The 30 days after the grace period when an expired domain can still be restored. |
Reference
- DNS recordsEvery DNS record type explained, with examples and a live lookup.
- Domain extensions directoryWho runs each popular extension, its rules and who it suits.
- List of domain registrarsEvery accredited registrar in the world, with its extensions and API.
- GlossaryShort definitions of domain and portfolio terms.
Put what you've learned to work.
Lemon Domains keeps every domain you own in one list, across registrars, with expiry dates, DNS and changes, and an AI assistant that can answer questions about all of it.