what is .io domain?

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British Indian Ocean Territory

he ccTLD (country code top level domain) and the internet country code for British Indian Ocean Territory

.IO can be used to substitute for the acronym i/o, or input/output

About the British Indian Ocean Territory

Located in the Indian Ocean, the British Indian Ocean Territory is an archipelago south of India, about halfway between Africa and Indonesia. This area includes the entire Chagos Archipelago of 55 islands. The combined area of these islands is 21,004 square miles, about one third the size of Washington D.C. Currently there are no indigenous habitats on these islands. In the 1960's and 70's, approximately 1,200 former agricultural workers in the Chagos Archipelago were relocated to Mauritius and the Seychelles. In November 2000 they were granted the right of return by a British High Court ruling. However, this ruling was overturned in 2008, finding no right for the natives to return. By November 2004, approximately 4,000 United Kingdom and United States military personnel and civilian contractors were living on the island of Diego Garcia in a joint naval support facility.

There are no restrictions on .IO registrations

Anyone can register a .IO domain name, similar to .COM, .NET, or .ORG. To register a third-level .IO domain name you must be a resident of the British Indian Ocean Territory.

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reference: https://www.name.com/domains/io