The Priority Signs
Priority signs basically regulate the right-of-way. They are shaped as downward triangles or the International yield signs (B1); red octagons for stop signs (B2); and, yellow diamond with white border (B3) for priority road. However, B3 is not used in the United States.
Generally, the uses of these signs depend on the regions. For instance, all-way stop signs are used in the US and Canada, but not in Europe. Yield signs and stops signs should be used only where traffic condition warrant. The downside of using too much signs is that it reduces effectiveness of the sign itself.
