Fire support is long-range firepower provided to a front-line military unit. Typically, fire support is provided by artillery or close air support (usually directed by a forward observer), and is used to shape the battlefield or, more optimistically, define the battle. Warships, for example, have long provided naval gunfire support. Artillery observers allow adjusting fire. Fire support has been used since the advent of cannons in warfare as artillery. Fire support, as an extension, is the marriage of artillery to the forces in contact. It is the direct ability to properly use artillery. It is distinct from direct fire, which is provided by the forces in contact.
Line companies in standard Heavy Brigade Combat Teams of the US Army often use Fire Support Teams (FSTs) mounted in forward support vehicles to observe and adjust fire.