Antacids are stomach acid neutralizers, or substances which counteract stomach acidity. Generally. They do so by raising the pH in order to reduce the hydrochloric acid.
Regular Websites
The Mayo Clinic's offering about oral antacids, including Pepto Bismol, Kaopectate, Tums, and Rolaids, consists of a description of both symptoms and various antacids used to treat those symptoms, and potential adverse effects. - Antacid (Oral Route)
http://www.mayoclinic.com/health/drug-information/DR602357
Family Doctor: Antacids and Acid Reducers
Provides an article and accompanying video in which a physician explains heartburn and acid reflux, and then goes on to describe antacids and over-the-counter acid reducers, which work with which conditions, and who should not take them. - Family Doctor: Antacids and Acid Reducers
http://familydoctor.org/online/famdocen/home/otc-center/otc-medicines/854.html
Article on iVillage delves into sodium bicarbonate, magnesium, and aluminum hydroxide and how they work. Also lists conditions of concern and potential side effects and interactions. - Your Total Health: Antacids
http://yourtotalhealth.ivillage.com/antacids.html