Islamist terrorists involved in the 11 March 2004 Madrid attacks attempt to bomb the Spanish high-speed train AVE near Madrid; the attack is thwarted.

Islamism is a range of religious and political ideological movements that believe that Islam should influence political systems. Its proponents believe Islam is innately political, and that Islam as a political system is superior to communism, liberal democracy, capitalism, and other alternatives in achieving a just, successful society. The advocates of Islamism, also known as "al-Islamiyyun", are usually affiliated with Islamic institutions or social mobilization movements, emphasizing the implementation of sharia, pan-Islamic political unity, and the creation of Islamic states.

Terrorism, in its broadest sense, is the use of violence against non-combatants to achieve political or ideological aims. The term is used in this regard primarily to refer to intentional violence during peacetime or in the context of war against non-combatants. There are various different definitions of terrorism, with no universal agreement about it. Different definitions of terrorism emphasize its randomness, its aim to instill fear, and its broader impact beyond its immediate victims.

The 2004 Madrid train bombings were a series of coordinated, nearly simultaneous bombings against the Cercanías commuter train system of Madrid, Spain, on the morning of 11 March 2004—three days before Spain's general elections. The explosions killed 193 people and injured around 2,500. The bombings constituted the deadliest terrorist attack carried out in the history of Spain and the deadliest in Europe since the bombing of Pan Am Flight 103 in 1988. The attacks were carried out by individuals who opposed Spanish involvement in the 2003 US-led invasion of Iraq.

Alta Velocidad Española (AVE) is a high-speed rail service operated by Renfe, the Spanish State railway company.