In theoretical physics, supergravity (supergravity theory; SUGRA for short) is a field theory that combines the principles ofsupersymmetry and general relativity. Together, these imply that, in supergravity, the supersymmetry is a local symmetry (in contrast to non-gravitational supersymmetric theories, such as the Minimal Supersymmetric Standard Model). Since the generators of supersymmetry (SUSY) are convoluted with the Poincare group to form a super-Poincare algebra, it can be seen that supergravity follows naturally from supersymmetry. All traditional literature on supergravity is generally written in terms of Cartan connections. Like any field theory of gravity, a supergravity theory contains a spin-2 field whose quantum is the graviton. Supersymmetry requires the graviton field to have a superpartner. This field has spin 3/2 and its quantum is the gravitino. The number of gravitino fields is equal to the number of supersymmetries. SUGRA, or supergravity, was discovered in 1976 by Dan Freedman, Sergio Ferrara and Peter van Nieuwenhuizen, but was quickly generalized to many different theories in various numbers of dimensions and additional (N) supersymmetry charges. Supergravity theories with N>1 are usually referred to as extended supergravity (SUEGRA). Some supergravity theories were shown to be equivalent to certain higher-dimensional supergravity theories via dimensional reduction (e.g. N = 1 11-dimensional supergravity is dimensionally reduced on S7 to N = 8, d = 4 SUGRA). The resulting theories were sometimes referred to as Kaluza-Klein theories as Kaluza and Klein constructed in 1919 a 5-dimensional gravitational theory, that when dimensionally reduced on circle, its 4-dimensional non-massive modes describe electromagnetism coupled to gravity. This book gives an overview of supergravity and the applicable theories using the latest peer-reviewed information."