Drug screening is a process used to detect the presence of illegal substances or prescription medications in a person's system. This testing can be conducted through various methods, including urine, blood, saliva, or hair samples. Drug screenings are commonly used by employers, law enforcement, and healthcare providers to ensure safety and compliance with regulations. The results of a drug screening can help identify substance abuse issues, monitor medication adherence, or determine fitness for duty in certain jobs. It is important to note that drug screening tests can vary in sensitivity and specificity, which may affect the accuracy of the results.