  This thesis is based on the publications arXiv:1106.4253, arXiv:1206.2920,
arXiv:1210.2590. We construct warped "AdS_4 x S^2 x S^2 x \Sigma" type IIB
supergravity solutions dual to the infrared fixed points of all 3d N=4 linear
and circular quivers. We provide checks of the correspondence by evaluating the
supergravity action in a large N limit and by matching it with the computation
of the free energy obtained from matrix models. To complete previous work, we
establish the holographic dictionary for the more general supergravity
solutions corresponding to domain walls (non-compact \Sigma) and dual to 4d SYM
CFT coupled to a 1/2 BPS 3d defect. We also use our evaluations of the free
energy to show that the F-theorem is verified for RG-flow relating
T^{\rho}_{\hat\rho}(SU(N)) SCFTs.
