A domain name looks like a single string of text, but it is actually built from several distinct parts, each with its own name and job. Once you can read those parts, every web address becomes easier to understand — you can tell the brand from the extension, spot a subdomain, and know exactly what you are choosing when you register a name. It is a small piece of knowledge that quietly makes you more fluent in how the web is organised.

This guide breaks a domain name down piece by piece: the top-level domain, the second-level domain, subdomains, and the extra elements around them like the protocol and www. You will see how the parts fit together in a clear hierarchy, why they are read from right to left, and how they relate to what you actually register and own.

The big picture: a hierarchy read right to left

A domain name is a hierarchical system of parts separated by dots, and the key to reading it is knowing the order runs from right to left — from the most general on the right to the most specific on the left. This is the reverse of how we normally read, which is why domains can seem confusing until the pattern clicks.

Take blog.example.com. The rightmost part, .com, is the broadest level (the category). Moving left, ‘example’ is the specific brand or site name. Furthest left, ‘blog’ is a particular section within that site. Each dot marks a step down into greater specificity, like narrowing from a country to a city to a street.

With that hierarchy in mind, the individual parts each have a proper name and role. The three you will meet most often are the top-level domain, the second-level domain, and subdomains — and understanding them covers almost every address you will ever see.

The Top-Level Domain (TLD)

The top-level domain is the suffix at the very end of the address — the .com, .org, .net, or country code like .uk or .jp. It sits at the top of the hierarchy and signals a general category or country. Originally, different TLDs implied different purposes: .com for commercial, .org for organisations, .net for networks — though today .com is used broadly by almost everyone.

There are a few kinds of TLD. Generic TLDs (gTLDs) like .com, .org, and newer ones like .io or .app are the most common. Country-code TLDs (ccTLDs) like .uk, .ca, or .de point to a specific country. And some TLDs are sponsored or restricted, meaning only certain organisations can use them. The registry that runs each TLD sets its rules.

The TLD you choose affects perception and sometimes availability. A .com is the most recognised and trusted for most sites, which is why it is usually the first choice — but the right TLD depends on your audience, your brand, and whether your preferred name is free.

The Second-Level Domain (SLD)

The second-level domain is the main, unique part of the address — ‘example’ in example.com, or ‘google’ in google.com. It sits just to the left of the TLD, and it is the part you actually choose to represent your brand, business, or project. When people talk about “picking a domain name”, this is really the part they mean.

The SLD is the heart of your web identity. It is what people remember, type, and associate with you, so it carries the most weight in how memorable and brandable your domain is. A short, clear, easy-to-spell SLD makes your whole address stronger, while a long or confusing one works against you.

Together, the SLD and TLD form your registrable domain — example.com — which is the unit you register and own. Everything else (subdomains, paths) is built on top of this core pairing. Get the SLD right, and you have the foundation of a strong domain.

Subdomains

A subdomain is an optional part added to the front of your domain, before the SLD, used to organise a distinct section of your site. Common examples are blog.example.com, shop.example.com, or mail.google.com. The subdomain sits at the far left of the hierarchy because it is the most specific part — a particular area within the broader site.

Subdomains are created and managed by you, the domain owner, once you hold the registrable domain — you do not register them separately or pay extra for them. They let you separate content or functions, such as putting a blog, a store, or a support portal on its own subdomain while keeping everything under one brand.

The most familiar subdomain of all is ‘www’, as in www.example.com. Though it is technically a subdomain, it is so conventional that most sites treat www and the bare domain as the same destination, redirecting one to the other. You can structure subdomains however suits your site, giving you flexibility without buying more domains.

The parts that aren’t really the domain

A few elements that appear in a full web address are not actually part of the domain name itself, and separating them clears up common confusion. The protocol — the https:// at the very start — tells the browser how to connect (securely, in this case), but it is part of the URL, not the domain. You never register a protocol; it is added automatically.

Similarly, anything after the domain — a path like /about or /blog/post, query parameters, or an anchor — belongs to the URL of a specific page, not to the domain. The domain is only the SLD-plus-TLD core (with any subdomain), while the URL wraps that domain in a protocol and a path to point to an exact page.

So in https://blog.example.com/posts/welcome, the domain portion is blog.example.com (subdomain + SLD + TLD), while https:// and /posts/welcome are URL elements around it. Knowing where the domain ends and the URL begins is what lets you read any address precisely.

How the parts relate to DNS and hosting

The parts of a domain are not just labels — they map onto how the domain system actually routes traffic. The TLD’s registry knows which nameservers are responsible for your registrable domain, and those nameservers hold the records that point your domain (and any subdomains) to the right servers. This is how a name resolves to a website.

Subdomains are particularly useful here because each one can point somewhere different. You could have your main site on one server, your blog subdomain on another, and your mail subdomain handled by an email provider — all under the same registrable domain, directed by DNS records. The hierarchy of names gives you a flexible way to organise where each part points.

So the structure you read from right to left also reflects a structure of control: you own the registrable domain, and from there you manage the subdomains and records that decide where everything leads. Understanding the parts is the first step to managing them.

A quick worked example

Put it all together with one address: https://shop.mybrand.co.uk/products/shoes. Reading the domain from right to left, .uk is the country-code top-level domain (a UK site), .co is a second-level label used within many country TLDs, mybrand is the distinctive name, and shop is a subdomain marking the store section. The https:// and /products/shoes are URL elements, not part of the domain.

Here the registrable domain — the part actually registered and owned — is mybrand.co.uk, because .co.uk works as the effective extension for UK sites. The ‘shop’ subdomain was added by the owner to organise the store, and the path points to a specific product page. One address, several clearly identifiable parts.

Once you can dissect an address like this, no domain looks mysterious. You can immediately see the brand, the extension, any subdomain, and the page path — and you know exactly which piece you register, which you create yourself, and which belong to the URL.

Frequently Asked Questions

What are the main parts of a domain name?

The three core parts are the top-level domain or TLD (the extension, like .com), the second-level domain or SLD (the unique name you choose, like ‘example’), and optional subdomains (like ‘blog’ in blog.example.com). Together the SLD and TLD form the registrable domain you own.

What is the difference between the SLD and the TLD?

The TLD is the suffix at the end (.com, .org, .uk) that signals a category or country. The SLD is the unique name just before it (‘example’ in example.com) that represents your brand. You choose the SLD; the TLD is a fixed extension run by a registry. Together they make example.com.

Is www part of the domain name?

Technically, ‘www’ is a subdomain, not part of the core registrable domain. The core domain is the SLD plus TLD, like example.com. Most sites treat www and the bare domain as the same place and redirect one to the other, so both reach your site, but the registered domain is example.com.

What is a subdomain?

A subdomain is an optional part added to the front of your domain to organise a section of your site, such as blog.example.com or shop.example.com. You create and manage subdomains yourself once you own the domain, at no extra cost, and each can point to a different server via DNS.

Is the https:// part of the domain name?

No. The https:// is the protocol, which tells the browser how to connect. It is part of the full URL, not the domain name. The domain is just the SLD-plus-TLD core (with any subdomain); the protocol and any path after the domain belong to the URL of a specific page.

Which part of a domain name do I actually register?

You register the second-level domain plus the top-level domain together — for example, example.com. That combination is the registrable domain you own. Subdomains like blog.example.com are then created by you for free, and paths and protocols are URL elements you do not register.

The bottom line

A domain name is a hierarchy of parts separated by dots and read from right to left, from general to specific. The top-level domain (.com, .org, .uk) is the extension signalling a category or country; the second-level domain (the unique name like ‘example’) is the brand you choose; and subdomains (like ‘blog’) are optional front sections you create yourself. Together the SLD and TLD form the registrable domain — example.com — that you actually own.

The protocol (https://) and any path after the domain are parts of the URL, not the domain itself, so knowing where the domain ends and the URL begins lets you read any address precisely. These parts also map onto how DNS routes traffic, with your nameservers directing the domain and each subdomain to the right place. Learn to dissect an address, and every web address — and every choice you make when registering one — becomes clear.

When you are ready, you can start with Hostinger and use code PROTIPS for the reader discount. A domain reads right to left: TLD (extension), SLD (your brand), and optional subdomains — with SLD+TLD the part you register.