What is "Gluten", And why is it bad for me ?

Many people suffer from an intolerance to gluten, the protein found in grains and the many foods made from them.
Even for those who don't suffer from celiac disease, the autoimmune disorder triggered by gluten, some doctors are recommending that their patients cut back or eliminate gluten from their diets, according to this health.com story posted on the CNN.com website.