A variable- (also changeable-, electronic-, or dynamic-) message sign or message board, often abbreviated VMS, VMB, CMS, or DMS, and in the UK known as a matrix sign, is an electronic traffic sign often used on roadways to give travelers information about special events.

Variable message signs (VMS) are permanently-installed or portable electronic roadside signs operated remotely by traffic management centers (TMC) to post traveler information messages to inform drivers of incidents, travel times, detours, special events, and other useful road conditions or travel information.