system that checks all data that has been handled after an improper shutdown. It also intermediates peering between itself, source file servers ("trackers") and other clients, thereby yielding distribution efficiencies. The client also enables users to create and share torrent files. Release history BitTorrent DNA BitTorrent DNA (BitTorrent Delivery Network Accelerator) is a program designed to speed up the viewing of streaming video, downloading software (with or without the BitTorrent protocol) and playing online video games. It does so by distributing the end users' downloads between each other. In this way, the developers intend that content providers should take less load on their servers so the end users can receive the content faster. It runs in the background whenever the operating system is running. BitTorrent DNA is different from traditional BitTorrent in that it relies on publisher HTTP servers in order to provide publishers with guaranteed minimum data delivery rate, as well as give publishers control over content delivery (peers must connect to the origin server before they can reach other peers), and collect information about content delivery to share with the publisher. The quality of the file transfer is specified in terms of a long-term average bitrate for data and in terms of meeting deadlines when streaming. It also can give bandwidth to TCP and other traffic. DNA is also different from traditional BitTorrent in that it is a UDP-based protocol that has replaced regular TCP-based bandwidth throttling with a much more sensitive bandwidth management technique. Apart from being installed by third party websites and software companies, the program for end users is also installed when the official BitTorrent client is installed (starting with the rebranded version 6.0). However, it can be independently uninstalled. The first version of the DNA made it possible to keep the DNA application installed and yet temporarily stopped until the next system restart (through the system's control panel, in Windows XP). The DNA GUI was completely removed in the official BitTorrent version 6.1 and 6.1.1, but was re-introduced in version 6.1.2. Since October, 2007 BitTorrent DNA has been offered by BitTorrent, Inc. as a commercial service that content providers can purchase (for an undisclosed price) and as a free background program for end users. Company President Ashwin Navin launched the product claiming that "Implementing BitTorrent DNA on top of legacy infrastructure has the profound impact of allowing our customers to deliver a better user