.!BT File Extension
File TypeBitTorrent Incomplete Download File
What is a !BT file?
Partially downloaded file created by BitTorrent, a torrent downloading application; used for all in-progress downloads if the "Append .!bt to incomplete files" option is selected in the BitTorrent preferences.
NOTE: BitTorrent removes the temporary ".!bt" extension once the file has been fully downloaded. !BT files are only used by the Windows version of BitTorrent.