One-dimensional Hamiltonians, such as the XYZ quantum spin chain, exhibit quantum phase transitions. The universal behaviours at such critical points are described, in the continuum scaling limit, by Conformal Field Theories (CFTs). In the first instance, CFTs are characterized by a central charge c. Entanglement entropy provides a convenient means to numerically determine the central charge through the ``area law". In these three lectures, we review the application of Yang-Baxter methods and Corner Transfer Matrices to calculate the entanglement entropy and central charge for the unitary XYZ quantum spin chain and its specializations. The extension of these methods to other unitary and nonunitary models will also be discussed.