Signal smoke refers to the use of smoke signals as a method of communication, particularly in outdoor or remote settings. This technique involves creating smoke by burning specific materials, which can be seen from a distance. The color and density of the smoke can convey different messages, making it a useful tool for signaling in situations where voice communication is not possible. Historically, various cultures, including Native American tribes and the Ancient Chinese, utilized signal smoke to send alerts or messages over long distances. The practice relies on the visibility of smoke against the sky, allowing for effective communication across vast landscapes.