The aim of this presentation is to introduce the research I have carried out in recent years, which led to being awarded a Ramón y Cajal fellowship, and to outline the future goals of the project. I will cover the three main pillars of my work: the analysis of spectropolarimetric observations, the use and development of inversion codes (computational tools used to infer the physical parameters of the solar atmosphere from these observations), and the design of state-of-the-art instrumentation for ground-based, balloon-borne, and space telescopes. All of these efforts serve a common purpose: advancing our understanding of the Sun. Thus, I will also touch on some of the most compelling open questions in solar physics I have worked on, including the nature of quiet Sun magnetism and the energy release mechanisms behind solar flares.