0.9% saline, also known as normal saline, is a sterile solution made up of 0.9 grams of sodium chloride (table salt) dissolved in 100 milliliters of water. It is commonly used in medical settings for various purposes, including hydration, wound cleaning, and as a diluent for medications. This solution is isotonic, meaning it has the same salt concentration as the body's cells, which helps maintain fluid balance. 0.9% saline is often administered through an intravenous (IV) line, making it a vital tool in hospitals and clinics for patient care and treatment.