Criminology is a science that studies criminal behavior, the ordered set of empirical knowledge about crime, the offender, socially deviant conduct and the control of such conduct and the victim. The fundamental objects of study are crimes, whose definition is social and normative, and their perpetrators. In the past, attempts have been made to define "natural" crimes, shared as such by all cultures, but they have essentially led to nothing; crime, in this sense, cannot be understood as a biological or "absolute" fact, but as the result of a certain social definition that varies according to time (history) and space (geography), that is, it varies from culture to culture. Crime, law and culture are therefore concepts that are deeply interrelated.   Today, criminology is a rather eclectic discipline in methodological terms, precisely because it does not constitute a unitary science, but the place of application of knowledge acquired in various contexts and belonging to different disciplinary fields to the problem of crime. Traditionally, criminology has been concerned with the study of the personality of the delinquent, to which the main schools that developed in the clinical-psychological field since the birth of psychology as a science in the nineteenth century have contributed (experimental psychology, criminal anthropology, psychoanalysis and the main psychodynamic schools, behaviorist and more recently cognitivist schools, social-psychological schools, systemic and family dynamics schools; study of delinquency through the main psychodiagnostic reagents).Also important have been the contributions of the sociological schools that developed mainly in the United States: on the one hand, the sociology of the Chicago school, with subsequent developments (theory of differential associations, theory of subcultures, theories of social stratification, up to the contributions of the so-called "radical criminology"); on the other, in the wake of the social psychology of George Herbert Mead, interactionist and phenomenological sociology, with the contributions of the labeling theory and the study of criminal careers. Other research has studied the perception of the criminal phenomenon, and the related emotions (fear of crime) in the wider community. To obtain these results, criminology has used both quantitative techniques of investigation, and qualitative techniques (currently in development after the quantitative wave of the seventies and eighties of the last century) more aimed at studying in depth individual cases or small groups of perpetrators. We must not forget the methodologies connected to the interactionist schools, of the so-called "participant observation", in which the scholar participates directly in the phenomenon he intends to study.