In a previous blog ‘#31 BACKGROUND – COIN Warfare & the ISAF’s COIN Strategy: Battle for the Majority Population’, I briefly outlined the central theoretical doctrine and most important principles of Counter-Insurgency (COIN) warfare. This appendix consists of a more in-depth examination of insurgencies and is offered in the hope of supplying important additional information to political and military practitioners, with regard to insurgent armed rebellions and the politico-military counter-insurgency warfare required by governing authorities and their civilian and military forces to quell them. In particular, this appendix will address: (1) insurgency as a common form of warfare in human history; (2) several definitions of insurgency; (3) the central characteristics of insurgencies; (4) the psychological nature of insurgency warfare, and the 4 psychological effects insurgents seek to inflict on established governing authorities; (5) the 3 main forms of warfare used by insurgents, namely terrorism, guerrilla tactics and conventional war; (6) the life cycle of an insurgency, from beginning to end; and lastly (7) the inherent uniqueness of each particular insurgency.