The opioid crisis is a public health emergency characterized by the widespread misuse of prescription painkillers, heroin, and synthetic opioids such as fentanyl. Beginning in the late 1990s, increased opioid prescribing contributed to rising addiction rates and overdose deaths in the United States and other countries. The crisis has strained healthcare systems, impacted workforce productivity, and prompted regulatory, legal, and policy responses aimed at prevention, treatment, and harm reduction.