  It is known, since the 70's, that the large N 't Hooft limit of gauge
theories is related to string theories. In 1998, J. M. Maldacena identified
precisely such a relation: the so-called AdS/CFT correspondence which
speculates a duality between a large N strongly-coupled supersymmetric and
conformal Yang-Mills theory in four dimensions and a weakly-coupled string
theory defined in a five-dimensional anti-de Sitter AdS space-time. This review
aims at introducing concepts and methods used to derive, in the framework of
the gauge/string correspondence, the interaction potentials of mesons and
baryons at zero and finite temperature. The dual string configurations
associated with the different kinds of hadrons are described and their
behaviors at short and large distances are understood. Although the application
of Maldacena's AdS/CFT conjecture to QCD is not straightforward, being QCD
neither supersymmetric nor conformal, the AdS/QCD correspondence approach
attempts to identify the dual theory of QCD. Especially, the study of heavy
quark-antiquark bound-states leads to establish general dual criteria for the
confinement.
