What is the origin of the idiom "green light" and when to use it?

The origin of the idiom "green light" can be traced back to the early 20th century, specifically to the traffic signal system. The use of red, yellow, and green lights in traffic signals was introduced to regulate and control vehicular movement. The green light, being the third and final signal in the sequence, indicated that it was safe for drivers to proceed. This phrase is frequently used in business settings, project management, decision-making processes, and personal endeavors.