  In this Ph. D. Thesis we concentrate on the study of the extension of the
AdS/CFT correspondence to theories with less supersymmetry. In particular, we
search for the possibility of adding supersymmetric D-branes in type IIB
supergravity solutions which are dual to N=1 supersymmetric gauge theories in
four dimensions. In the probe approximation we perform a systematic analysis of
the possible supersymmetric D-brane configurations in backgrounds dual to N=1
superconformal field theories, firstly in the AdS_5xY^{p,q} solutions and then
in their generalisation to the AdS_5xL^{a,b,c} backgrounds. Some checks of the
correspondence between D-brane configurations and chiral operators of the dual
gauge theory are performed. We also analyse the possible supersymmetric
D5-brane configurations dual to defects (of codimension one and two) in N=1 SYM
theory in the framework of the Maldacena-Nunez solution. Beyond the probe
approximation, we develop techniques in order to take into account the
backreaction undergone by the type IIB supergravity solutions (dual to N=1
superconformal field theories and their extensions to cascading theories) due
to the addition of a number of flavour branes of the same order as the number
of colour branes which generate the unflavour background. The dual
interpretation of those flavour branes is given in terms of dynamical fields
transforming in the fundamental representation of the gauge group. Several
gauge theories features are matched, like beta functions, anomalies and the
duality cascade which describes the RG flow of the cascading field theories.
