  The aim of this dissertation is to review `Loop Quantum Gravity', explaining
the main structure of the theory and indicating its main open issues. We will
develop the two main lines of research for the theory: the canonical
quantization (first two chapters) and spin foams (third). The final chapter
will be devoted to studying some of the problems of the theory and what things
remain to be developed. In chapter 3 we will also include an example of a
simple calculation done in the frame of LQG: Schwarzschild black hole entropy.
