You may find below a list of illegal and legal addictive substances, which highlights the mechanism, effects, and treatment of nicotine, alcohol, benzodiazepines, cannabis, the opioids, psychostimulants i.e. cocaine and amphetamines; a comprehensive and concise shot highlights the nature of polydrug use. I am offering below material as a guide to those who wish to gain a general understanding of illegal and legal drugs; this material was offered to me as a postgraduate in the Institute of Psychiatry Psychology and Neuroscience at King’s College London.