.tf is the Internet country code top-level domain (ccTLD) for the French Southern and Antarctic Lands. Along with .fr, .nc, .pm, .re, .wf and .yt it is administered by AFNIC. Before October 23, 2004, Adamsnames, based in Cambridge, administered this TLD.
There is also an additional free service offering third-level .tf domains, under the name United Names Organisation. They occupy 14 second-level domains, including .eu.tf, .us.tf, .net.tf, and .edu.tf. They are run by the same company as smartdots.com, and are given away as URL redirections.
The French Southern and Antarctic Lands are territories either recognised as French or claimed but suspended under the Antarctic Treaty System France, and the domain name derives from the French, Terres australes et antarctiques françaises. Part of the French claim includes a section of the continent of Antarctica, creating an overlap between .tf and the general Antarctica domain .aq.
The .tf domain-name has popular usage for sites related to the game Team Fortress 2. Many of these sites are commonly used for marketing of virtual goods originating from Team Fortress 2 and, by extension, the Steam Community Market.