Today the Tor Project and Facebook announced that .onion web addresses, which allow anonymous users to browse online through Tor, have been formally recognized by the Internet Engineering Task Force. The IETF is responsible for determining which domains are designated as "special use domains," a subset of domains considered for registration based on special properties, and today the organization included .onion on that list.

The Tor Project says the recognition of .onion is a small step toward greater acceptance of services like Tor, but also has some immediate effects: it prevents ICANN from selling off the .onion domain, permanently keeping it within the realm of hidden services. "As a result, no one can buy .onion and there won’t be a conflict of interest," says Jacob Appelbaum, a privacy researcher at the Tor Project who helped write the draft proposal submitted to the IETF. The recognition from IETF also ensures that anyone hoping to create an address under the domain can do so free of charge, and will eventually make widely used software integration easier for anonymous users.

To submit the draft, the Tor Project partnered with Facebook; engineer Alec Muffett is listed alongside Appelbaum on the paper sent to the IETF. Last year, the company made the unexpected move of launching its own link for users who wanted access through Tor's hidden services. At the time, Facebook explained that it wanted to create an "experience more consistent with our goals of accessibility and security."

Appelbaum told The Verge that the registration is "one of the first but certainly not the last standardization process that we’re going to see."