This volume is written purely based on the requirement of UPSC Civil Services Main Examination. This will cater collectively to all the topics included under Internal Security Syllabus. The author has taken utmost care to keep the language of the contents very lucid and easily understandable to enable easy comprehension and retention. Relevant examples and illustrations have been added for better understanding along with adequate questions at the end of every chapter for practice. Important and useful reports of various committees and commissions are also included.