Xanax is the brand name for the drug Alprazolam, which is used to treat anxiety and panic disorders. It is a component of benzodiazepine drugs that acts on the brain to provide a calming and relaxing effect. It increases the impact of a neurotransmitter called GABA (Gamma-aminobutyric Acid), reducing message transfer between nerve cells. GABA's primary function is to reduce the initiation, sending, and receiving of messages from one nerve cell to the next, thereby reducing the symptoms of anxiety and panic attacks.

Xanax comes in a variety of doses that are distinguished by their color. A Yellow Xanax Bar, like a white or blue Xanax bar, contains 2mg of active Alprazolam and has the imprint of R039 on one side of the drug. The various manufacturing companies cause the color difference. Yellow Xanax Bars, also known as "Yellow School Bus" or "Yellow Bus." This is a common name among drug users and sellers who buy non-prescription Xanax. Yellow Xanax Bars are prescribed to patients with moderate to severe anxiety and panic attacks due to their higher dosage strength.