What is a .io domain? (2023)

Contents

1. What is a top-level domain (TLD)?
2. What is a .io domain?
3. What does .io stand for?
4. Why is .io so popular in the IT field and with tech start-ups?
5. Advantages and disadvantages of the .io domain

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The domain extension .io is a ccTLD, i.e., a country-specific, top-level domain, which was assigned to the British Indian Ocean Territory and introduced in 1997. The domain is administered by the domain registrar Internet Computer Bureau (ICB), which is based in the United Kingdom and since 2017 has been a subsidiary of the American group Afilias, which also administers the TLDs .info, .mobi, and .pro, among others.

From the very beginning, the .io domain was not meant to be a country-specific extension – which is not surprising given the fact that there are no legal permanent residents of the British Indian Ocean Territory. As such, any individual or legal entity can register a .io address regardless of residency or establishment, and 2 to 63 alphanumeric characters may be used. Only addresses with second-level domains like .com, .net, or .gov are blocked. In other words, registering a domain like mybusiness.net.io is not possible.

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Originally, the domain .io stood for Indian Ocean. However, nobody associates the top-level domain with the British overseas territory, the last remnant of which is the Chagos archipelago (a group of islands spanning around 40 sq mi). Probably hardly anyone who asks themselves the question “What does .io stand for?” is even aware that the TLD has a country-specific background.

So, instead of asking “What does .io stand for?” the question is rather “What meaning is attributed to the .io domain?”. Here, the following two functions of the domain can be highlighted as possible answers:

• Input/output (I/O or IO): In computer science, the abbreviation I/O or IO stands for input/output, i.e., the communication of information systems such as computers with the outside world. Similar to the generic TLD .app, for example, which is the perfect extension for developers of mobile apps, the .io domain is of particular interest for tech companies in light of this possible meaning.
• Domain hacks: The top-level domain .io is also significant as an ending for domain hacks. With a little creativity, web addresses such as rad.io or portfol.io can be generated using the clever combination of ending and domain name. A popular example is the domain rub.io, which the American politician Marco Rubio used for his election campaign in the 2016 presidential race.

In 1998, the fashion company Levi Strauss & Co. registered levi.io, the first web address under the ccTLD .io.

According to numbers published by w3techs.com approximately 0.5% of all websites are registered under the TLD .io (status: April 2021), achieving similar rankings with country-specific domains like .it (Italy) or .pl (Poland).

Its big popularity is mainly due to the meaning of the letter combination IO. Potential users such as developers or IT administrators, who are active in the IT sector, get a good idea of what the content of the site relates to simply by looking at the input/output abbreviation present in the domain. On the other hand, the domain extension also represents an easily readable and pronounceable alternative to classic, high-in-demand top-level domains and is therefore a good option if a desired name isn’t available anymore under .com etc.

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