[The Diamond Open Access scientific publishing model: birth, evolution and reflections on its sustainability]

The world of scientific publishing has undergone, in recent decades, a series of profound transformations supported by continuous technological innovations and strongly motivated by the movement born to promote free access (Open Access - OA) and without restrictions to scientific information. In this still evolving context, the Diamond Open Access model emerges in which journals and platforms do not require fees from authors or readers. In this article, after a brief overview of how scientific publishing has developed from the traditional publication model to OA and how we arrived at the Diamond OA model, the authors will focus on examining the latter in particular. The aim of this contribution, in fact, is to provide an account as exhaustive as possible of the numerous projects, initiatives and organizations that currently support and promote the Diamond OA model and, at the same time, to reflect on its sustainability and on the concrete problems that hinder its greater diffusion within the varied ecosystem in which scientific information moves today.