Spain has been one of the European democracies most affected by terrorism throughout the twentieth and twenty-first centuries. Terrorism perpetrated by Euskadi ta Askatasuna (ETA) has been the most intense one, but other groups have also perpetrated terrorist acts and even protracted terrorist campaigns. D. C. Rapoport's waves of modern terrorism provide the right historical framework for the main expressions of political violence in Spain to be placed in. ETA's activists found an endorsement for their violence in a set of nationalist ideals based on the exclusion of those not seen as nationalists and who opposed the nationalist aim of the creation of an entity called Euskal Herria. ETA's terrorism was not the only one present in Spain during the transition from dictatorship to democracy and throughout the consolidation of democracy in the country. Spain was also affected by terrorism linked to and/or inspired in a radical interpretation of Islam since the 1980s.