Artillery serves both offensive and defensive roles. The concept behind the use of artillery is to deliver casualties, confusion and mayhem to an adversary at substantial range, and ideally, out of the range of retaliation.
In an offensive, artillery is used to soften up an opponent before engagement with assault troops such as infantry, cavalry and mechanized artillery.
In defensive operations the objective of the use of artillery is to inflict substantial damage upon an attacker at a range sufficient to avert damage.
In recent conflicts, the roles of artillery and other long-range techniques such as aerial bombing have become more crucial so that the battle is practically over before ground troops are sent in or localized operations commence. The techniques used with employing artillery have changed as the capabilities of artillery and the design of fortifications have changed. It should be noted that it is realistically no longer possible to defend a position from a local range.