Intravenous therapy (IV) is a therapy that delivers liquid substances directly into a vein (intra- + ven- + -ous). The intravenous route of administration can be used for injections (with a syringe at higher pressures) or infusions (typically using only the pressure supplied by gravity). Intravenous infusions are commonly referred to as drips. The intravenous route is the fastest way to deliver medications and fluid replacement throughout the body, because the circulation carries them. Intravenous therapy may be used for fluid replacement (such as correcting dehydration), to correct electrolyte imbalances, to deliver medications, and for blood transfusions.