In medicine, saline (also saline solution) is a general phrase referring to a sterile solution of sodium chloride (NaCl, more commonly known as salt) in water, but is only sterile when it is to be placed parenterally (such as intravenously); otherwise, a saline solution is a salt water solution. The sterile solution is typically used for intravenous infusion, rinsing contact lenses, nasal irrigation, and often used to clean a new piercing. It is also a good medium to store an avulsed ("knocked out") tooth until it can be re-implanted by a dentist. Saline solutions are available in various formulations for different purposes. Salines are also used in cell biology, molecular biology, and biochemistry experiments.