Tom Clancy's Rainbow Six (often shortened to R6) is a tactical first-person shooter video game franchise by Red Storm Entertainment and Ubisoft based on the novel Rainbow Six by American author Tom Clancy. Critically and commercially successful the franchise revolves around a fictional international counterterrorist organization called Rainbow. Tom Clancy's Rainbow Six follows a secret international counterterrorist organization called "Rainbow" (or "Team Rainbow"; capitalization varies between "Rainbow" and "RAINBOW"). The series is set in the canon Tom Clancy's universe which is mostly shared with Tom Clancy's Splinter Cell and Tom Clancy's Ghost Recon.