.co is the Internet country code top-level domain ( ccTLD) assigned to Colombia. It is administered by .CO Internet S.A.S. , there are no registration restrictions on second-level .co domains; any individual or entity in the world can register a .co domain.
.co has become increasingly popular among tech startups. The .co domain is also used by many established brands for social and mobile media, such as Twitter (t.co), Google Inc. (g.co), Amazon.com (a.co), American Express (amex.co) and Starbucks (sbux.co).
.co domain names are available for registration globally through accredited registrars.
.CO Internet S.A.S from Bogotá, Colombia, was appointed as the manager for the .co TLD through a public procurement process that took place in early 2009. .CO Internet received the re-delegation approval as the manager of the .co TLD by ICANN on December 9, 2009, and received formal confirmation of the request by the United States Department of Commerce on December 23, 2009.
In a number of countries, .co is used as a second-level domain to mean "commercial" and domain registrants register second-level domains of the form .co.xx, where xx is the country code top level domain (e.g., .co.uk in the U.K. and .co.jp in Japan).
Some of the countries using .co as a second-level domain include India ( .in), Indonesia ( .id), Israel ( .il), the United Kingdom ( .uk), South Africa ( .za), Costa Rica ( .cr), New Zealand ( .nz), Japan ( .jp), South Korea ( .kr) and Cook Islands ( .ck).