Prevalence and patterns of drug use is one of the key indicators used by the EMCDDA to assess the drug situation in Europe. It helps with understanding patterns of use, risk perceptions, social and health correlates, as well as the consequences of the use of illicit drugs. This indicator makes use of a number of tools including data from general and school population drug surveys, as well as innovative new approaches such as wastewater-based drug epidemiology, and targeted surveys, including web surveys. On this page you can find a selection of the EMCDDA's resources on this topic.