The number of domain names on the Internet has now reached 400 million, according to recent reports. A domain name functions like an address for websites, making it easier for users to access online services without having to remember complicated numerical IP addresses. The .com extension, managed by the American company Verisign, is the most popular, with over 166 million domains registered. Domain names are also used in digital security, such as SSL certificates that verify a website's identity, although a new service called Let's Encrypt now also offers certificates for IP addresses directly. Domain names are broadly divided into two main types: country code top-level domains (ccTLDs) and generic top-level domains (gTLDs). ccTLDs are two-letter codes that represent specific countries or regions, such as .fr for France, .de for Germany, .cn for China, and others. These are typically managed by the governments of the respective countries. In contrast, gTLDs are three or more letters long and are usually managed by private companies or organizations. Examples include .com, .net, .ink, and .best. According to the latest data from the Internet Assigned Numbers Authority (IANA), which is part of the Internet Corporation for Assigned Names and Numbers (ICANN), there are 316 ccTLDs and nearly 1,300 gTLDs. In addition to these, there are around a dozen first-level extensions that are "sponsored," meaning they are managed by specific organizations or governments. For instance, .gov is managed by the U.S. Cybersecurity and Infrastructure Security Agency (CISA), .cat is for the Catalan language, .aero is for aviation-related sites, and .asia is for businesses in the Asia-Pacific region. In total, nearly 1,600 first-level domain extensions exist on the Internet, and this number is expected to grow rapidly. Recently, ICANN completed the second round of applications for new generic extensions, receiving nearly 1,600 applications. However, not all of these will be approved, and some may be duplicates, showing the high level of interest in expanding the domain name system. The Centralized Zone Data Service (CZDS) is used to gather official domain name data for nearly 1,100 extensions, including the three largest: .com, .net, and .org.