Drug testing is a scientific process used to detect the presence of illicit substances or prescription drugs in a person's bloodstream, urine, hair, sweat, or saliva. This testing is commonly used by employers, law enforcement, and sports organizations to ensure individuals are not using drugs that could impair their performance or pose a risk to others. Drug testing can also be used in clinical settings to monitor patients' compliance with prescribed medications or to identify potential drug abuse. Various methods of drug testing exist, including urine analysis, blood tests, hair follicle tests, and oral swab tests. The accuracy and reliability of drug testing methods can vary depending on the type of test and the substances being detected.