Internal Security is a crucial component of the UPSC Civil Services Examination, particularly in General Studies Paper III. It deals with threats to national stability arising within the country and measures adopted by the state to maintain peace, law and order, and sovereignty. Internal security covers issues such as terrorism, insurgency, left wing extremism, communalism, cyber security, organized crime, border management, and the role of security forces and agencies. Internal security differs from external security. External security focuses on threats from other nations, while internal security addresses challenges arising within the country. However, both are interconnected. Cross border terrorism, illegal migration, and external support to insurgent groups blur the distinction between internal and external threats. One of the major internal security challenges is terrorism. Terrorism involves the use of violence to create fear and achieve political, ideological, or re...