Criminology is one area of study/work within the context of Forensic Science (which also falls under the umbrella of criminal justice). Criminology is one of the common areas of focus within PhD programs.
According to definition, criminology is "the scientific study of crime as an individual and social phenomena." This, of course, is a basic definition. Further explanation defines criminology as "the science of crime rates, individual and group reasons for committing crime, and community or societal reactions to crime." In other words, research, research, research. Think university or high-level agency jobs here. And also, know that within criminology, you can select any of the above designated areas in which to focus your studies and research.
While it is only required that a criminologist obtain a masters degree, this can vary from setting to setting. For example, if you wish to conduct research for a university, or practice as a criminal psychologist, you will require a PhD. This distinction is an important one to make if you are trying to decide between being a masters level or a doctoral level criminologist.
