There is no universal agreement on the definition of terrorism.^[1][2] Various legal systems and government agencies use different definitions of terrorism. Moreover, governments have been reluctant to formulate an agreed-upon and legally binding definition. Difficulties arise from the fact that the term has become politically and emotionally charged.^[3] Since 1994, the United Nations General Assembly has condemned terrorist acts using the following political description of terrorism:

Criminal acts intended or calculated to provoke a state of terror in the general public, a group of persons or particular persons for political purposes are in any circumstance unjustifiable, whatever the considerations of a political, philosophical, ideological, racial, ethnic, religious or any other nature that may be invoked to justify them.^[4]

In the United States of America, terrorism is defined in Title 22 Chapter 38 U.S. Code § 2656f as “premeditated, politically motivated violence perpetrated against noncombatant targets by subnational groups or clandestine agents”.^[5]

In general, terrorism is classified^{[by whom?]} as:

• The use of violence or of the threat of violence in the pursuit of political, religious, ideological or social objectives
• Acts committed by non-state actors (or by undercover personnel serving on the behalf of their respective governments)
• Acts reaching more than the immediate target victims and also directed at targets consisting of a larger spectrum of society
• Both mala prohibita (i.e., crime that is made illegal by legislation) and mala in se (i.e., crime that is inherently immoral or wrong