Different Domain Types And Best Practices For SEO

Updated by Chima Mmeje — November 11, 2024.

Domain names are the unique, human-readable Internet addresses of websites. It is important to distinguish between domain and web hosting, where the domain name is the address users enter to access a website, and web hosting refers to the server space where website data is stored. They are made up of three parts: a top-level domain (sometimes called an extension or domain suffix), a domain name (or IP address), and an optional subdomain.

There are several types of domains, each with its own characteristics and uses. Understanding the different types of domains can help website owners choose the most suitable and effective domain name for their online presence. Selecting the right type of domain can influence your site’s visibility, credibility, and overall success.

Let’s look at each of these elements more closely:

Top-level domain

Top-level domain (TLD) is the formal term for the suffix that appears at the end of a domain name, also known as domain name extensions. Some example of top-level domains include:

• .com
• .net
• .org
• .edu

These domain name extensions are part of the domain name system hierarchy, which classifies and organizes domains at the highest level of name resolution.

While we’re probably all familiar with the TLDs above, there are actually over 1,000 possible TLDs from which webmasters can choose. This includes things like .book, .clothing, .dog, and .lifeinsurance (to name a few), as well as TLDs associated with specific countries or territories like .uk (United Kingdom) or .dk (Denmark). These country- (and sometimes region-)specific TLDs are known as country code top-level domains, or ccTLDs.

Subsets of Top-Level Domains include:

• Generic Top-Level Domains (gTLDs)

Generic Top-Level Domains (gTLDs) are a type of top-level domain that is not tied to any specific country and can be used by anyone. Examples of gTLDs include .com, .net, and .org. These domain extensions are used to categorize websites into different types and are the most common type of domain extension. Managed by the Internet Corporation for Assigned Names and Numbers (ICANN), gTLDs are available for registration through accredited registrars. Their widespread recognition and versatility make them a popular choice for businesses and individuals alike.

• Country-code Top-Level Domains (ccTLDs)

Country-Code Top-Level Domains (ccTLDs) are specific to particular countries or regions, denoted by a two-letter code such as .us for the United States or .uk for the United Kingdom. These top-level domains indicate a website’s country of origin and are often used by businesses and organizations that operate within a specific region. Using a ccTLD can help target local audiences more effectively and can signal to search engines the geographical focus of your content, which can be beneficial for local SEO.

• Sponsored Top-Level Domains (sTLDs)

Sponsored Top-Level Domains (sTLDs) are a type of top-level domain sponsored by a specific organization or community. These domains are usually denoted by a three-letter code, such as .edu for educational institutions or .gov for government agencies. sTLDs are used to identify websites affiliated with a particular organization or community and are often employed by businesses and organizations within specific industries or sectors. By using an sTLD, entities can clearly signal their association with a recognized group, enhancing their credibility and trustworthiness.

Second-level domain (SLD)

A second-level domain (SLD) is the part of a domain name that appears directly to the left of the top-level domain. Essentially, it is the core of your web address and often represents your brand or business name. For instance, in the domain name “example.com”, “example” is the SLD. This part of the domain is crucial as it is what users will remember and associate with your website. Choosing a relevant and descriptive SLD can significantly impact your branding and SEO efforts, making it easier for users to find and recall your site.

Domain name

Domain names are the second level of a domain’s hierarchy (after the top-level domain). When selecting a domain name, it is crucial to check the availability of your desired domain using registry tools and consider various extensions if the primary choice is unavailable. Domain names on a specific TLD (called a root domain, discussed below) are purchased from registrars and represent the specific, unique location of a website. In the following examples, the domain names are bolded:

• www.example.com
• https://moz.com
• www.blogspot.com

Search engines do use the keywords in domain names as a ranking factor (which explains the existence of domains like “where-to-buy-the-best-donuts-in-Seattle.com”), but tread lightly when thinking about optimizing your root domain for search engines: One of the specific functions of Google’s algorithm is to combat these keyword-stuffed exact-match domains.

If you’re trying to decide on a domain name, check out this How to Choose a Domain Name Whiteboard Friday.

Root domain

While the term “root domain” was originally created in the context of DNS (domain-name servers), it typically refers to the combination of a unique domain name and a top-level domain (extensions) to form a complete “website address.” The root domain is a key part of the domain hierarchy, which includes the top-level domain and second-level domain. Your website’s root domain is the highest page in your site hierarchy (probably your homepage). Individual pages or subdomains can be built off the root domain, but each page URL must technically include the same root domain in order to be a part of your website.

Examples of root domains include:

• moz.com
• Ilovedogs.net
• PawneeIN.gov

All the pages on a single website have the same root domain (discussed below), and no two different websites can have the same root domain.

Because root domains represent whole websites instead of specific web pages, counting linking root domains instead of linking URLs (pages) can be a more accurate way to judge the size of your site’s inbound link profile (generally speaking, more linking root domains is better). By investigating the top 500 sites on the web, for example, you can see what kind of impact the number of linking root domains and other important link metrics have on a site’s rankings and popularity. Backlink tools like Link Explorer can help you uncover the total number and specific identity of root domains linking to your site.

Subdomain

Subdomains, also known as third level domains, are the third level of a domain’s hierarchy and are parts of a larger top-level domain. They are added in front of the root domain and separated from the domain name with a period.

These third level domains can help organize website content into distinct sections, enhancing user navigation.

For example, “blog.example.com” and “english.example.com” are both subdomains of the “example.com” root domain. Subdomains are free to create under any root domain that a webmaster controls.

The two most common subdomain choices are:

• http://www.example.com (“www” is the subdomain)
• http://example.com (has no subdomain)

These are also the subdomains that commonly result in canonicalization errors

Internationalized domain names (IDNs)

Internationalized domain names (IDNs) are domain names that include non-Latin characters, allowing users to access web addresses in their native languages and scripts. This is particularly beneficial for regions where languages use characters outside the Latin alphabet. To ensure compatibility with the Domain Name System, IDNs undergo a process called “Punycode encoding.” This process converts the non-Latin characters into a format that the system can understand. By enabling users to register domain names in their local languages, IDNs enhance accessibility and make it easier for users to find and remember domain names.

By understanding these different types of domains and their specific uses, you can make more informed decisions when selecting a domain name that aligns with your goals and target audience.

To maximize search engine-referred traffic, it is important to keep each of the following elements in mind: Having a relevant domain that accurately reflects your business or industry can enhance search engine rankings and increase the likelihood of acquiring backlinks.

1. Make your domain name memorable

Strive for domain names that are short, easy to remember, easy to type, and easy to say.  This is valuable for word-of-mouth advertising because those visitors will need to visit your domain directly, but it also matters for processing fluency. An implicit cognitive bias, processing fluency is the concept that we remember and have more positive associations with things that we can easily say and easily think about, and that includes pronounceability in our own minds. So, stay away from domain names that include numbers or other non-standard characters, use unusual spelling, or are longer than about 15 characters or so.

Because of search engine's growing reliance on accessibility and usability as a ranking factor, the easier a domain (or URL) is to read for humans, the better it is for search engines.

From "15 SEO Best Practices for Structuring URLs"

2. Use broad keywords when sensible

If you can include a keyword that helps make it obvious what your business does while keeping your domain name catchy, unique, and brand-friendly, go for it. But, stay away from domain names that might be considered "keyword-rich" or "keyword-targeted" (such as best-pancake-pans-for-pancakes.com or senior-eldercare-retirement-home-finder.com) We mentioned this earlier, but it's worth mentioning again: While these types of domain names once carried weight as a ranking factor, their tendency to be associated with low-quality content means searchers (and search engines) may now view these keyword-dense domain names with a negative bias.

What's more, in recent years Google has made several changes that have de-prioritized sites with keyword-rich domains that aren't otherwise high-quality. Having a keyword in your domain can still be beneficial, but it can also lead to closer scrutiny and a possible negative ranking effect from search engines, so tread carefully. For more on this topic, read The Exact Match Domain Playbook: A Guide and Best Practices for EMDs.

3. Avoid hyphens if possible

If your domain name is two words (like www.examplesite.com), you may want to separate the words with a hyphen for readability: www.example-site.com. But, keep in mind that use of hyphens also strongly correlates with spammy behavior and decreases domain name readability and memorability. For that reason, generally, no more than one hyphen should be used (if any must be used at all). 

4. Avoid non-.com top-level domains (TLDs)

When a webmaster registers a domain name, they will often be given the option to buy additional TLDs. In order to maximize the direct traffic to a domain, bias towards purchasing the .com TLD. If the .com TLD for a domain name you're looking to purchase isn't available, Rand recommends leaning towards .net. , .co, or a known ccTLD as alternatives.

Additionally, it is not recommended that SEO-conscious webmasters purchase low-quality TLDs such as .biz, .info, .ws, .name, etc. as a means of increasing traffic. Because they're less commonly known, these TLDs receive substantially less traffic than the more widely known domains as well as may be more frequently associated with spammy behavior.

5. Favor subfolders/subdirectories over subdomains

Search engines keep different metrics for domains than they do for subdomains, so even though Google itself has stated that — from a ranking perspective — content in subdomains and subdirectories is treated roughly equally, it's still recommended that webmasters place link-worthy content like blogs in subfolders rather than subdomains (i.e. www.example.com/blog/ rather than blog.example.com).

The notable exceptions to this are language-specific websites. (i.e., en.example.com for the English version of the website).

6. Don't sweat over domain age

The notion that the age of a domain (i.e. how long it's been registered) is an important SEO ranking factor is a myth. When asked about domain registration length, Google's Matt Cutts said, "To the best of my knowledge, no search engine has ever confirmed that they use length of registration as a factor in scoring. If a company is asserting that as a fact, that would be troubling. The primary reason to renew a domain would be if it's your main domain, you plan to keep it for a while, or you'd prefer the convenience of renewing so that you don't need to stress about your domain expiring."

What does matter to Google (albeit to varying degrees) are things like how long it's been since your site was first crawled or since the first inbound link was recorded. Even so, though, Matt Cutts assures that "the difference between a domain that's six months old and one year old is really not that big at all."

7. Moving domains

If a webmaster needs to move one domain to another, there are several critical factors to consider, including setting up the redirects on a page-to-page basis such that sub-folders and deep content pages are redirected to corresponding sub-folders and deep content pages on the new domain. SEOs should avoid redirecting all pages from one domain to the homepage of another domain. For more information, see Achieving an SEO-Friendly Domain Migration: The Infographic

Are domain names important to SEO?

Broadly speaking, while your domain name itself isn’t considered to be a direct Google ranking factor, elements of your domain name may play into your overall SEO success. A domain name serves as a stand-in for a website's IP address, making it easier for users to access websites without needing to recall specific numerical identifiers. These include elements such as memorability, length, keyword usage, brand-ability, and more.

Does changing your domain name affect SEO?

Changing your domain name can impact your SEO, as you are effectively migrating your site from one address to another. To avoid losing traffic during a domain name migration, we suggest following these SEO migration best practices

Does the domain extension affect SEO?

The domain extension, commonly referred to as the Top-Level Domain (TLD), generally isn't considered a Google ranking factor, except in the area of International SEO. In this case, having a specific country code top-level domains (ccTLDs) can indicate to search engines which country your content is targeted at. 

Is .com best for SEO?

While the .com domain extension is by far the most popular Top-Level Domain (TLD), there is no indication it is given any special treatment by search engines. That said, consumers often trust .com extensions more than others, and having a .com version of your domain is often seen as desirable. 

Keep learning

• How to Choose a Domain Name
• What is Domain Authority?
• URLs
• 15 SEO Best Practices for Structuring URLs
• Top 500: Moz's list of the top 500 sites on the web, based on Domain Authority and other link-based metrics
• Top-Level Domains: Official list of Top-Level Domains by the Internet Assigned Numbers Authority (IANA)

Root Servers' Locations: The location of the world's root servers plotted on a Google map.