Warning signs are used by private companies at the workplace in order to protect the employees of potential risks. They are also used on the public roads under the form of traffic signs. A traffic warning sign indicates a hazard that may not be readily apparent ahead on the road.
As an international rule, in most countries the public roads traffic usually take the shape of an equilateral triangle with a thick red border and white background. However, from country to country both the color and thickness of the border and of the background may vary. For example, in the People’s Republic of China they appear with a yellow background and a black border.
In Greece, Iceland, Sweden, Finland, Serbia, Poland, Bosnia and Herzegovina, and the Republic of Macedonia the traffic signs have an amber background and a red border. In Svalbard, the polar bear warning sign displays a white bear on black background. Some countries such as Spain, Norway, and France have adopted an amber or orange background for construction signs or road work.
In some countries in place of the standard triangular shape, they have a diamond shape. In Mexico, Canada, the United States, Ireland, Australia, New Zealand, Thailand, Malaysia, Indonesia, Japan, and most of South America the warning signs are diamond-shaped and black on a yellow background, while temporary signs such as the construction signs are black on an orange background.
Most usually contain a symbol but they can also contain only text. In the United Stated they are based on a standard, while in Europe they are based on the Vienna Convention.
Even older than that is the usage of first roadside signs, the ancient milestones giving distance measures. In the past, prior to the 19th century, hazard warnings were rare. The occasional specimens were usually specific warning about horse-drawn vehicles backing up. More complex signage systems emerged in the 20th century, with the appearance of motorcars. As the vehicle speeds and the traffic volume increased, nighttime use capability and sign visibility gained more significance.
Modern traffic signs can indicate any potential condition, obstacle, or hazard requiring special attention. Due to necessity to comply with the European regulations, the British government will have some road signs totally redesigned or axed. Some of these in presently in place in Britain are baffling, misleading, and confusing to many motorists, while some unusual warning signs are straightly weird or funny. This is especially true if some tourists from overseas view them for the first time.