The conference takes place in Trieste on the occasion of the centenary of Margherita Hack's birth and is held in a hybrid format, with a preference for in-person participation and a limited number of online presentations. The meeting is intended to deliver a historical retrospective on Margherita’s work and legacy, focusing on astrophysical spectroscopy, both in the stellar and extragalactic fields. We also have sessions dedicated to the present ground based and space facilities and to future cutting-edge instrumentation. Given Margherita's commitment to the field of outreach and dissemination of astronomy, and her strong link with the town, we have planned a parallel program of events dedicated to the public.