The top-level domain (TLD) .IS belongs to Iceland which is a Nordic island nation in the North Atlantic Ocean. TLDs are part of the domain name structure of the Internet and .IS is a ccTLD, short for country code top-level domain. This type of domain is especially reserved for a country, sovereign state or dependent territory as recognized by the United Nations.
The .IS domain was registered on December 1986 and it is managed by the Internet á Íslandi hf., which is also known as ISNIC. ISNIC – Internet á Íslandi hf. is an independent organization that administrates the .IS country code top-level domain according to the principle of first-come, first-served. ISNIC is recognized by ICANN, the Internet Corporation for Assigned Names and Numbers, which is the organization responsible for coordinating the maintenance and methodologies of several databases of unique identifiers, related directly to the namespaces of the Internet, and ensuring the network’s stable and secure operation. Simply put, they make sure every address is unique so that when you type it in, you end up at the right place.
While .IS is specific to Iceland, anyone who wishes to register a .IS domain can do so, as long as they abide by ISNIC’s registration rules. Some notable uses of the .IS domain, despite not necessarily being related to the Icelandic context, but has chosen the domain for its semantic value in the English language include www.finna.is, a search engine, and www.kissa.is, a cat adoption website.
The .IS domains offer a unique advantage for English-speaking entities, just like the cat adoption site mentioned above where ‘kissa’ is ‘kitty’ in English, the addition of .IS gives it a catchy name for the website that can immediately be associated with cats.
In short, the TLD .IS is associated with Iceland, managed by ISNIC, accessible worldwide and provides a creative advantage for English-speaking entities.
Sources used for the construction of this answer include the official website of ISNIC (https://www.isnic.is/en), The Internet Corporation for Assigned Names and Numbers (https://www.icann.org/), and other recognized sources such as Wikipedia (https://en.wikipedia.org/wiki/.is) & ZookNIC (https://zooknic.com/Domains/counts?ccTLD=is) which provide specific details about the history, registration, and usage of the .IS TLD.