HEALTH:
Medline Plus
Medlineplus.gov should be the first place you look for any health-related information. 

There is a dictionary and encyclopedia to give brief descriptions of conditions, anatomical terms, and various procedures.

There is a link to a site to help patients and physicians find out about clinical trials.

There are 165 slide show tutorials covering common conditions tests, and surgical procedures.

You can look up prescription drugs, over the counter remedies, and herbal supplemements.

Best of all, you can find links to various specialty organizations with comprehensive information about various conditions, which is written by physicians
UpToDate
UpToDate.com is a treasure trove of medical information.  Many medical sites have a great deal of information about a handful of conditions.  Others offer a smidge of information about a lot of conditions.  UpToDate offers a pretty good range of topics and fairly comprehensive information.

Information is written by physicians, and is approved by professional organizations.   Check out the information on a common foot condition,
plantar fasciitis, a frequent cause of heel pain.  And when they recommend something like exercises to treat a condition, there are graphics illustrating what to do.
MedStory
Have you ever tried to use Google for a health condition? There's good information out there, but it's like looking for a needle in a haystack.

What if there were a search engine that focused on sites with useful information? Well there is such a site, called Medstory. It will even prioritize results based on whether you are looking for personal health or research purposes.

Then it gives you useful suggestions for focusing your search.
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