The article attempts to fi nd an answer as to what internal security is today and how it can be defi ned and placed in the conceptual framework of other types of security, such as external and national security. As the article underlines, the era of separating the concepts of internal and external security has become out of date, which is due to the fact that security is in a process of constant evolution, alongside with its defi nitional scope. Over the years, the process of the evolution of internal security in Poland has involved the change of both the very institutional system, understood as the administrative apparatus of internal security, and the phenomenon of internal security itself, which has been and still is being infl uenced by the changing nature of security threats. The article describes the process of the evolution of internal security in Poland, conditioned both by the socio-economic development and by the transformation of the political system. Attention is also drawn to the technological and information revolution in the context of its huge impact on subsequent changes in the so-called phenomenon of internal security globalisation, which creates a system of interdependencies in the area of security, including international security.