The Chemical Evolution of Galaxies

Metals -- heavy elements synthesized during various phases of stellar evolution or during supernova explosions -- play a fundamental role in shaping galaxy evolution. In fact, their relative abundances, spatial distribution, and scaling with galactic properties reflect the constant interplay between star-formation, nucleosynthesis, and gas flows that drive the cycle of baryons in-and-out of galaxies across the cosmic time. This chapter aims at offering a concise introduction to the methodologies used to measure elemental abundances in galaxies and the basics of chemical evolution modeling. We also provide a brief overview of the current observational framework, including metallicity scaling relations, the study of relative chemical abundances, the distribution of metals within and beyond galaxies, and how these properties evolve with redshift, drawing on both extensive literature and recent developments, and aiming to highlight well-established findings alongside ongoing challenges in this rapidly advancing field.