Several illustrative examples are presented in this tutorial review to demonstrate the utility of 2D correlation spectroscopy, especially in life science applications. A set of IR spectra for a model protein system, which is undergoing complex thermally induced changes in the secondary structures, is analyzed by 2D correlation spectroscopy. The method of constructing 2D correlation maps from temperature-dependent IR spectra and their interpretation procedure are described. The resolution of overlapped protein IR bands by 2D correlation is demonstrated, and sequential order of spectral intensity changes is determined. Newly emerging techniques in the field, such as Pareto scaling, positive null-space projection, and 2D codistribution analysis, are discussed in some detail, in addition to the traditional application of 2D correlation spectroscopy.