Twinning is not an uncommon effect in crystallography, although it has long been considered to be one of the most serious potential obstacles to structure determination. The use of area detectors has much facilitated the detection of twinning and the treatment of diffraction patterns from twinned crystals. We have written software which enables many twinning problems to be resolved with just a mouse-click. This available as a stand-alone program (http://www.ccp14.ac.uk/ccp/web-mirrors/rotax/), and in the programs WinGX Oscail and Crystals.