Medication refers to substances used to diagnose, treat, or prevent diseases and medical conditions. They can be classified into various categories, including prescription medications that require a doctor's approval and over-the-counter medications that can be purchased without a prescription. The effectiveness of medication often depends on proper usage, dosage, and adherence to prescribed guidelines. Medications can come in various forms, such as tablets, capsules, injections, and topical applications, each designed to deliver therapeutic effects to the body efficiently.