Addiction is characterized by loss of control over substance use, often operationally defined as continued use of substances despite knowledge of adverse consequences. The exact cause of addiction is not known, but it's hypothesized that both environmental and genetic factors play a crucial role in the predisposition of this disease. When an individual abruptly stops using a drug or an addictive substance, withdrawal symptoms often take place, which include vomiting, nausea, loss of appetite and depression. Not much is known about the neurobiology of addiction and treatment remains a huge challenge. Current research aims at identifying the neurological circuit of addiction as well as the key neurotransmitters and biological markers involved in this disease. In this paper, I will first begin by giving you an overview of the major substances that cause addiction as well as the most common addictive behavior patterns. Second, I will discuss the major findings that have been done using animal models of addiction, and describe in more details the role that brain imaging technology plays in improving our understanding of drug abuse. Finally, a closer look will be taken at the behavioral and pharmacological approaches frequently employed to treat addiction.