The phenomenon of terrorism, in its destructive nature, has been noticeable since the dawn of time, as it has had a direct impact on both national and non-state entities. Nevertheless, it was only in the 20th century that it was characterised on the basis of past acts of aggression. These were defined as attacks against the person, group, state or international organisation perpetrated by a non-state actor. Today, the general definition assumes that it is a form of warfare used to achieve specific goals, with the intention of extorting changes proclaimed by terrorists. The actions are undertaken against civilians. They are characterised by violence and aggression and cause destabilisation, confusion and anxiety in society. For this reason, it is vital to deliver a complex description of the definition offered not only by the Polish researchers but also French (France is the most attacked state in the European Union), as well as internationally.