This chapter aims to present a theoretical foundation on hacking, focusing on the perpetrator's profile, his modus operandi, and typologies. First, a conceptualization and characterization of the phenomenon's key terms is presented. Next, the chapter addresses the historical evolution of the perception of the phenomenon, from the moment of its emergence to the current understanding. The most prominent typologies in the scientific literature will be described, which seek to distinguish the perpetrators of the behaviors according to criteria related to their practice. While focusing on the cybercriminals, the chapter emphasizes the hacker's figure, directing the review on their sociodemographic profile and contextual aspects. Finally, the personality factors prevalent in hackers are characterized, namely according to the big five model and the dark triad model. This chapter, using criminological lens, will increase the knowledge of the hackers and its modus operandi. The implications of this knowledge will be outlined.