Drug screening is a process used to detect the presence of illegal substances or prescription medications in a person's system. This can be done through various methods, including urine, blood, saliva, or hair tests. Drug screenings are commonly used in workplaces, schools, and medical settings to ensure safety and compliance with regulations. The results of a drug screening can help identify substance abuse issues and guide appropriate interventions. It is important to note that drug screening tests can vary in sensitivity and specificity, meaning they may not always provide definitive results. Follow-up testing may be required for confirmation.