Written by an algebraic topologist motivated by his own desire to learn, this well-written book represents the compilation of the most essential and interesting results and methods in the theory of polynomial invariants of finite groups. From the table of contents: - Invariants and Relative Invariants - Finite Generation of Invariants - Construction of Invariants - Poincaré Series - Dimension Theoretic Properties of Rings of Invariants - Homological Properties of Invariants - Groups Generated by Reflections - Modular Invariants - Polynomial Tensor Exterior Algebras - Invariant Theory and Algebraic Topology - The Steenrod Algebra and Modular Invariant Theory