.io domains are popular with new startup companies. IO is also used in IT as an abbreviation for input/output, which makes the .io domain useful for domain hacks. IO also stands as an abbreviation for Internet Organization. In addition, .io domains are often used for open source projects and online services.
^Beattie, Russell (2013-02-12). "The rise of .io domains for well crafted web services". Retrieved 2014-04-24. "There's lots of open source projects (Redis, Brackets, Launcher), a few mobile-app landing pages (Avocado, X-Ray), a ton of new web apps and services, several conference pages (Lightning, Renaissance, Resonate) and a few older companies or organizations who've changed their name to take advantage of a cleaner .io name."