What is a group categorized by common topics or geography in the domain naming system known as?

A group categorized by common topics or geography in the domain naming system is known as a Top-Level Domain (TLD). TLDs are the last part of a domain name, appearing after the final dot, such as .com, .org, .net, and country codes like .uk or .ca. They help in classifying domains based on either the type of organization (e.g., .org for organizations, .edu for educational institutions) or the geographical location (country code TLDs).

Understanding TLDs is crucial because they not only indicate the nature or purpose of the website but also play a vital role in the domain name hierarchy, serving as the highest level of the domain name system. This categorization assists users in identifying the type of content or the geographic origin of the information on the website, enhancing navigability and trust in online resources.