WebMD is an American

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 corporation which provides health information services. It was founded in 1996 by Jim Clark and Pavan Nigam as Healthscape, later Healtheon

Healtheon

Healtheon was a dot-com startup company, created in Silicon Valley by Dr. James H. Clark and Pavan Nigam. Healtheon's business plan was to streamline communication and paperwork in the United States health care system...

, and then acquired WebMD in 1999 to form Healtheon/WebMD. The name was later shortened to WebMD.
It is primarily known for its public Internet site, which has information regarding health and health care, including a symptom checklist, pharmacy information, "drugs information", blogs of physicians with specific topics and a place to store personal medical information.