From the HON website:
HON has been created for improving the quality of information intended to both patients and medical professionals for facilitating quick access to the most relevant and up-to-date medical discoveries.HONcode is the oldest and the most used ethical and trustworthy code for medical and health related information available on Internet.The HONcode is designed for two target audiences: the general public and the web publisher, actively involving the site owner in the process of certification. The HON Foundation is a Non-Governmental Organization, internationally known for its pioneering work in the field of health information ethics, notably for the establishment of its code of ethical conduct, the HONcode. The HONcode is the most widely accepted reference for online health and medical publishers. Currently the HONcode is used by over 6,800 certified websites, covering 118 countries.
HON web site http://www.healthonnet.org/ is visited by 27,000 visitors world-wide per day.