The book presents a comprehensive analysis of internal security systems in the Visegrad Group countries: Poland, the Czech Republic, Slovakia and Hungary. The authors discuss key institutions responsible for protecting citizens and infrastructure in each country, including: special services, police, fire brigades and border guards. The researchers try to present different approaches to threats such as migration, terrorism and cybersecurity through an analysis of internal security institutions. The publication presents the development of security policy since 1989, taking into account integration with NATO and the EU and responses to contemporary challenges such as the COVID-19 pandemic and the war in Ukraine.