Road signs are needed to help keep everyone safe. Their shape and colour tell you a lot.
Signs can be divided into three types:
Compulsory signs are usually red or blue. They tell you what you must or must not do.
Warning signs are usually diamond in shape. They warn you to be careful for your own safety, the safety of other road users or of road workers.
Permanent warning signs are yellow. Sometimes the fluorescent signs are a yellow/green colour.
Temporary warning signs are orange and black.