Fuchsian Reduction is a method for explicitly representing solutions of nonlinear PDEs near singularities. The technique has multiple applications in soliton theory, Einstein's equations and cosmology, stellar models, laser collapse, conformal geometry and combustion. Developed in the 1990s for semilinear wave equations, Fuchsian Reduction research has grown in response to those problems in pure and applied mathematics, where numerical computations fail. The exposition unfolds systematically in four parts, with theory and applications nicely interwoven. prototypes for future new applications. Background results in weighted Sobolev and Holder spaces as well as Nash--Moser implicit function theorem are provided. Most chapters contain a problem section and notes with references to the literature. This volume can be used as a text in graduate courses in PDEs and/or Algebra or as a resource for researchers working with applications to Fuchsian Reduction.