An introductory review of the foundations of the Attractor Mechanism in extremal black holes in d=4 supergravity theories will be given. The issues of the classification of black hole attractors, of their stability and of the definition of an effective potential in the scalar manifold will be addressed. Finally, some recent developments will be shortly considered, such as the charge orbits and the moduli spaces of attractor solutions in N=2 and extended supergravities, and the generalization of the Attractor Mechanism to intersecting configurations of black branes in higher dimensions.