Warning labels are most often placed on machines, devices, chemicals, in transport or in production or storage floors. The main role of warning labels is to signal the risk of danger associated with improper use of equipment. They provide information about, for example, rotating and sharp elements of machines, harmful content, products in transport, or OHS and fire protection rules.

The information contained on the warning labels, the dimensions of the labels, the colour and the positioning on products or machinery are usually strictly defined by legal requirements.