This chapter looks into various conceptualizations of terrorism. Most terrorism scholars view terrorism as a distinctive phenomenon when compared with other forms of political violence. Terrorism is most often defined as the use of violence for the purpose of generating a psychological impact beyond the immediate victims or any sort of political motive. However, how to accurately define terrorism has long been the subject of contentious debates both within policy-making and the terrorism studies literature of the past fifty years. The chapter then lists the levels of analysing terrorism. These are: definition, conceptualization, and pejorative labeling. It notes how the psychological impact and terrorism is viewed as fundamental in understanding terrorism.