Yellow traffic signs always denote a change in the road situation. The yellow is a clear indication of a warning and is universally recognized as such. These are often in the shape of a diamond and may display black text information or just simply a black graphic clearly outlining the situation.
These signs can include such things as a road surface changes, bicycle routes, emergency vehicle lanes, warnings for animals on the road, curves or turns in the road and much more. They are also always made from a reflective substance so that they are also visible at night when car lights shine on them.
These signs are always found on the roadside and usually are placed at an adequate distance prior to the hazard or road change taking place. This gives drivers time to react and slow down if needed.