  We review the background, theory and general equations for the analysis of
equilibrium protein unfolding experiments, focusing on denaturant and
heat-induced unfolding. The primary focus is on the thermodynamics of
reversible folding/unfolding transitions and the experimental methods that are
available for extracting thermodynamic parameters. We highlight the importance
of modelling both how the folding equilibrium depends on a perturbing variable
such as temperature or denaturant concentration, and the importance of
modelling the baselines in the experimental observables.
