The seminar will provide an overview of the chemical evolution of galaxies across the cosmic epochs and it is primarily based on an extensive review on this topic written with Filippo Mannucci (and which will hopefully appear on arXiv before the date of the seminar), although in this seminar a little more weight will be given to recent results obtained by our teams. The scaling relations between metallicity and galaxy physical properties, metallicity gradients, relative chemical abundances, metallicity properties of different classes of galaxies, the metals content budget, and the information which is inferred to further our understanding of galaxy evolution, are some of the topics that will be discussed. Although the seminar will be mostly focussed on the chemical evolution of galaxies, circumgalactic medium, galaxy clusters and, more broadly, galaxy environments will also be discussed. The seminar will finally outline open issues and the prospects of tackling them with forthcoming observing facilities and new theoretical models and simulations.