A material safety data sheet (MSDS) is a written description of each hazardous chemical used in a workplace. MSDSs are the primary source of information about workplace chemicals for employers and workers. Each contains comprehensive technical information about a particular substance and explains the risks, precautions, and potential solutions related to hazardous chemicals, both during normal work and in emergency situations. The MSDS is at the heart of OSHA's Hazard Communication standard.