Xanax XR or Alprazolam is a medicine that is categorized under the Benzodiazepines class of drugs. This class of drug works on the unbalanced chemical in the brain that is held responsible for creating a disturbance in the proper functioning of the brain. Xanax XR is an extended-release version of Xanax or Alprazolam which means the medicine will start showing its effect a little later as expected and will stay in your system for a longer period of time. People buy Xanax online so that the information that they are not able to get just by purchasing the drugs from the drug store will get it from the online pharmacies that are selling these medicines at reasonable prices.