There is no universally agreed, legally binding, criminal law definition of terrorism. Common definitions of terrorism refer only to those violent acts which are intended to create fear (terror), are perpetrated for a religious, political or ideological goal, and deliberately target or disregard the safety of non-combatants (civilians). Some definitions now exclude acts of state terrorism and some also include acts of unlawful violence and war. The use of similar tactics by criminal organizations for protection rackets or to enforce a code of silence is usually not labeled terrorism though these same actions may be labeled terrorism when done by a politically motivated group.
The word "terrorism" is politically and emotionally charged, and this greatly compounds the difficulty of providing a precise definition. Studies have found over 100 definitions of “terrorism”. The concept of terrorism may itself be controversial as it is often used by state authorities (and individuals with access to state support) to delegitimize political or other opponents, and potentially legitimize the state's own use of armed force against opponents (such use of force may itself be described as "terror" by opponents of the state).
Terrorism has been practiced by a broad array of political organizations for furthering their objectives. It has been practiced by both right-wing and left-wing political parties, nationalistic groups, religious groups, revolutionaries, and ruling governments. An abiding characteristic is the indiscriminate use of violence against noncombatants for the purpose of gaining publicity for a group, cause, or individual.