We review the kinetic theory of one-dimensional nonlinear oscillator chains, of which the most famous example is the Fermi-Pasta-Ulam-Tsingou equation. We provide detailed, though not rigorous, accounts of the microscopic to mesoscopic, and mesoscopic to macroscopic limits: derivation of the kinetic wave equation and hydrodynamic limit. We also present the state of the art of the mathematical theory, including proofs. We discuss the connection to two famous problems of Mathematical Physics: the Fermi-Pasta-Ulam-Tsingou paradox, and the derivation of Fourier's law. Finally, many open problems and possible directions for future research are proposed.