Merck & Co., Inc., Rahway, NJ, USA (known as MSD outside of the US and Canada) is a global healthcare leader working to help the world be well. From developing new therapies that treat and prevent disease to helping people in need, we are committed to improving health and well-being around the world. The Manual was first published in 1899 as a service to the community. The legacy of this great resource continues as the MSD Manual outside of the United States and Canada. Learn more about our commitment to Global Medical Knowledge.