A flammable sign is any visual indication that there is a potential fire hazard in the area. These signs vary greatly in design and purpose. Most signs have a generic warning on them that tell of danger, or to keep away. Other signs will warn about more specific hazards, such as flammable gas, flammable fumes, or that no flammable items are allowed beyond a certain point. All of these warning signs are put into place for safety reasons, in order to avoid potential injury. In chemistry, the most important of these signs is the NFPA Hazard symbol.