GHS stands for the Globally Harmonized System of the Classification and Labeling of Chemicals. It is a set of guidelines for ensuring the safe production, transport, handling, use, and disposal of hazardous materials.
The GHS was developed by the United Nations as a way to bring into agreement the chemical regulations and standards of different countries. In short, it is an international attempt to get everyone on the same page. The hope is that every country will incorporate the tenets of the GHS into their own chemical management systems with the goal of making the international sale and transportation of hazardous chemicals easier, as well as making workplace conditions safer for all employees exposed to chemical hazards.

The U.S. officially adopted the GHS on March 26, 2012. OSHA’s adoption is actually a revision of the Hazard Communication Standard to align with the GHS. OSHA calls this revision HazCom 2012. 
The GHS is not a global law or regulation– a common misconception – it is actually a system. Think of the GHS as a set of recommendations or collection of best practices. No country is obligated to adopt all or even any part of the GHS. Countries can, however, pick and choose those pieces of the GHS they wish to incorporate into their own regulations (this is called the building block approach). Each adopting country is solely responsible for its enforcement within its jurisdiction. To date, over 65 countries have adopted GHS or are in the process of adopting GHS.

The most noticeable changes brought by GHS for most organizations will be changes to safety labels, safety data sheets, and chemical classification. As an example, the GHS refers to safety data sheets as SDSs, dropping the M from material safety data sheets (or MSDSs) as most American companies are used to. The GHS also standardizes the content and formatting of SDSs into 16 sections with a strict ordering. Labels also look quite different, with six standardized elements that include specific language depending upon chemical classification.

GHS is meant to be a logical and comprehensive approach to:
-Defining health, physical, and environmental hazards of chemicals (although environmental hazards are outside OSHA’s jurisdiction)
-Creating classification processes that use available data on chemicals for comparison with the defined hazard criteria
-Communicating hazard information in a prescribed and uniform way on labels and safety data sheets