The issue of calculating at strong coupling is a hard problem in physics. The discovery of gauge-gravity duality at the end of the Twentieth Century provides a novel means of calculating in a large-N gauge theory at strong coupling. In this thesis we apply the method of gauge-gravity duality to a variety of questions. Firstly we review the string theory background material and then introduce the gauge-gravity duality. We discuss the procedure for adding fundamental representation matter to gravity duals. We present a method for calculating the quasinormal frequencies associated to mesonlike excitations in non-zero temperature gravity duals and apply it to excitations of bosonic and fermionic type. We study the thermal phase transition in a somewhat QCDlike gravity dual deformed by the presence of a relevant operator and find a plausible transition between a QCD-like confining phase and a high temperature phase which is just the generic black hole geometry. Finally we examine the effect of chemical potential on the behaviour of fundamental representation matter in a gravity dual and look for superconductivity-like behaviour.