Traffic lights are structures placed at the intersection of two roads. Using different colored lights, they let drivers know when it is their turn to go across the intersection. Wherever there's an intersection, there's the possibility of an accident if two cars try to cross at the same time. The purpose of a traffic light is to keep wrecks and other traffic accidents from happening by allowing traffic to proceed in an orderly manner, one direction at a time. Signals connected to red lights also indicate when it's safest for pedestrians to cross, reducing the number of people on foot who get hit by cars.

The first traffic light ever built was installed in England in 1868 to direct traffic at the British Houses of Parliament. It was operated by hand by a policeman. Tragically, the newfangled device exploded a little over a year after it was installed, killing the policeman. Today, traffic lights are much improved. The lights change by themselves, and can even be connected to other traffic lights to improve the flow of traffic. The first automated, interconnected set of traffic lights was turned on in Houston in 1922. Fortunately, the newer models are also much less explosive!

Although there are some regional variances as far as what different lights mean, the basic color code for traffic lights is the same all over the world. Red means "stop," green means "go," and yellow means "prepare to stop," although some impatient people interpret it to mean "go faster." The Texas Transportation code spells out how motorists are supposed to behave at a Texas red light: 

An operator of a vehicle facing only a steady red signal shall stop at a clearly marked stop line. In the absence of a stop line, the operator shall stop before entering the crosswalk on the near side of the intersection. A vehicle that is not turning shall remain standing until an indication to proceed is shown. After stopping, standing until the intersection may be entered safely, and yielding right-of-way to pedestrians lawfully in an adjacent crosswalk and other traffic lawfully using the intersection, the operator may: (1) turn right; or (2) turn left, if the intersecting streets are both one-way streets and a left turn is permissible. (Texas Transportation Code § 544.007d)