  We provide a review of gauge field theories with higher spin, focusing on the
classical theory of massless bosons in flat Minkowski spacetime. A brief
introduction to the concept of spin is provided along with a historical review
of some of the most important problems and accomplishments in higher spin
theory, followed by a review of familiar lower spin theories. Using a
particularly elegant formalism, we examine the free higher spin theory and the
theory coupled to a generic external current. For both of these theories, we
review their constrained and the unconstrained formulation, focusing our
attention on the latter. We also review the existing literature, confirming the
results for the non-local unconstrained formulation and correcting some
calculational errors. We briefly discuss the geometrical motivation behind the
construction of the basic building blocks of the theory and we entertain the
possibility of there being a single equation of motion for all bosonic higher
spin fields. Some explicit calculations obtained using computer-assisted
methods are provided in the appendix, along with the relevant computer code.
