Wikipedia
PirateBrowser is an Internet browser by The Pirate Bay used to circumvent Internet censorship. It was released on 10 August 2013 on the tenth anniversary of The Pirate Bay. It is a bundle of Firefox Portable, the FoxyProxy addon, and the Vidalia Tor client with some custom configurations. According to TorrentFreak it had been downloaded more than 2,500,000 times by October 2013.
The browser circumvents site-blocking in countries including, according to the Pirate Bay Web site, Belgium, Denmark, Finland, Iran, Ireland, Italy, The Netherlands (Not any more), North Korea and the United Kingdom. This allows users to access some websites otherwise blocked, usually by government ban or threat of legal action, by Internet Service Providers (ISPs) in these countries.