Most pictograms have a distinctive red "square set on one of its points" border. Inside this border is a symbol that represents the potential hazard (e.g., fire, health hazard, corrosive, etc.). Together, the symbol and the border are referred to as a pictogram. Pictograms are assigned to specific hazard classes or categories.

The Hazard Communication Standard (HCS) requires pictograms on labels to alert users of the chemical hazards to which they may be exposed. Each pictogram consists of a symbol on a white background framed within a red border and represents a distinct hazard(s). The pictogram on the label is determined by the chemical hazard classification.

The pictograms are: exploding bomb, flame, flame over circle (oxidization), gas cylinder, corrosion, skull and crossbones (acute toxicity), health hazard, environmental hazard, and exclamation point. Each pictogram may have one or more corresponding hazard statements, which describe the nature and degree of the risk posed by the chemical.

A hazard pictogram is an image on a label that includes a warning symbol and specific colours intended to provide information about the damage a particular substance or mixture can cause to our health or the environment.