“Dangerous Goods are articles or substances which are capable of posing a risk to hearth, safety, property or the environment and which are shown in the list of dangerous goods or which are classified according to the Regulations.” (IATA Dangerous Goods Regulation 52nd Edition Section 1, 1.0 pg. 1)
BASIS OF REGULATIONS

The United Nations Subcommittee of Experts on the Transport of Dangerous Goods develops recommended procedures for the transport of all dangerous goods (excluding radioactive materials), by all modes of transport. The International Civil Aviation Organization (ICAO) uses these recommendations to develop regulations for the safe transport of dangerous goods by air.  These are published in the ICAO Technical Instructions.

The International Air Transport Association (IATA) have also developed regulations that contain all of the requirements of the ICAO Technical instructions, but include additional restrictions. The IATA Dangerous Goods Regulations have been developed to reflect industry standards and practical considerations. Therefore, compliance with the IATA Dangerous Goods Regulations helps to ensures your compliance with all airlines, not only IATA member airlines. Please note that many airlines and countries publish additional variations, more restrictive conditions, which are specific to the particular country or airline. These variations are published in the IATA DG Regulation but may be imposed at any time.

Regulations change and it is advisable that you stay up to date with these changes by regularly checking industry web sites.
The below links provide addendums and changes to the DG Regulations along with shipper documents and checklist to assist with DGR compliance.