Social behaviour has broad implications for the survival and reproduction of an organism. Social behaviours often reflect rather complex mechanisms. Through a variety of interactions, individuals establish social relationships (dominant/subordinate, friend/foe, potential mate/mating partner, kin/non-kin). In some cases this may require aggressive physical altercations and more passive interactions such as ritualistic competitions, behavioural sequences, behavioural postures, and other forms of signalling. Social interactions are dependent on context and environmental influences. Understanding the functional significance and mechanisms driving various social behaviours will require empirical comparative studies with careful consideration of environmental factors. This book provides information on the idea of social behaviour in different animals being affected by evolution and the environment.