Historically, Par Cans were named for the fact that the fixture, the "can," held a Parabolic Aluminum Reflector. It was the lamp that gave the fixtures their namesake. Some lamps would be wide flood, while others might be a narrow spot. Some were circular in output, while others were oval. The oval ones could be rotated to adjust which way you wanted the light to go. Today, while we still call these conventional fixtures "par cans," similar-use LED fixtures have also been wrapped into this category. All in all, "par cans" are simply wash lights that can be colored.- Louie Lumen