What is the definition of a third-level domain name?

A third-level domain name is a subdivision within a second-level domain name. It appears to the left of the second-level domain name and to the right of the top-level domain name in a URL. For example, in the URL "www.example.com," the "www" part is considered a third-level domain name.

Domain names are hierarchical, with the top-level domain (TLD) being at the highest level, followed by the second-level domain (SLD), and then the third-level domain (subdomain) if it exists.

For instance, in the URL "mail.example.com", "com" is the TLD, "example" is the SLD, and "mail" is the third-level domain. Third-level domains provide a way to further organize and categorize websites within a domain. They can also be used to create subdomains for specific purposes, such as "blog.example.com" or "store.example.com".

Third-level domain names are typically chosen by website owners or administrators based on their preference or organizational needs. They can help in creating memorable URLs and organizing website content. However, it is important to note that the availability and usage of third-level domain names may depend on the specific domain registrar and hosting provider.

about third-level domain names:

1. Structure: A third-level domain name is placed in front of the second-level domain and after the top-level domain. It consists of a string of characters separated by dots. For example, in "support.example.com", "support" is the third-level domain.

2. Subdomains: Third-level domains are often referred to as subdomains because they act as subdivisions within the main domain. They can be used to create separate sections or branches of a website for various purposes like blogs, forums, or specific departments.

3. Control and Customization: Third-level domain names allow website owners to have more control and customization options. Each subdomain can have its own unique content, design, and functionality. This flexibility is useful for organizations with multiple services or locations.

4. URL Hierarchy: The usage of third-level domains contributes to the URL hierarchy. As you move from left to right in a URL, the higher-level domains come first and then the lower-level domains. This structure helps users navigate websites visually and distinguish different sections.

5. DNS Configuration: Configuring a third-level domain requires modifying the domain's DNS (Domain Name System) settings to point to the desired server or hosting provider. Proper configuration ensures that requests to the subdomain are directed to the correct destination.

Rewording:
google.com is classified as a second-level domain, while mail.google.com falls under the category of a third-level domain.

Domain names serve as unique identifiers for websites on the internet. They are structured in levels, with the top-level domain (TLD) being the highest level, followed by the second-level domain (SLD), and potentially further subdomains. Understanding the different levels of domains is essential for website owners and developers to effectively manage and organize their online presence.

Domain is a part of the internet's hierarchical domain name space that is identified by a unique domain name.

A domain name is a symbolic representation that must be unique within its domain. The complete domain name consists of the names of all the domains it is a part of, separated by dots. For instance, en.wikipedia.org represents the third-level domain en, which belongs to the second-level domain wikipedia, which in turn is part of the org domain, which ultimately belongs to the root domain. A domain name serves as a means to address internet nodes and network resources (such as websites, email servers, and other services) in a user-friendly format.

A domain zone refers to a set of domain names at a specific level within a particular domain. For example, the zone wikipedia.org encompasses all third-level domain names within the wikipedia domain. The term "domain zone" is predominantly used in technical contexts when configuring DNS servers, including tasks like zone maintenance, zone delegation, and zone transfer.

You mean that little prefix before your actual domain that everyone thinks magically boosts SEO or organizes their site better?
It's just a glorified DNS label. Like "api.myservice.com" or "beta.myservice.com," it's mostly used to separate environments or services.

Developers love to throw subdomains everywhere to "modularize" their architecture, but often it just complicates CORS policies, SSL certs, and cookie scopes. So yeah, third-level domains are handy, but don't kid yourself - they're just DNS entries, not some secret sauce for web success.