This course is part of the S³ School initiative, carried out in the framework of the European projects OSCARS and EVERSE. The S³ School is a structured training program dedicated to advancing skills in open science, reproducible research, and sustainable scientific software development. It brings together researchers, engineers, and students to promote best practices in scientific computing, with a strong emphasis on transparency, reproducibility, and the long-term sustainability of research software across disciplines.

In an era where scientific discovery is driven by code, how can we ensure our results are more than just a "one-off"? This talk explores the essential transition from "black box" scripts to transparent, reproducible research. We dive into the "reproducibility crisis," the power of the FAIR principles, and the technical pitfalls—from shifting dependencies to compiler quirks—that threaten scientific integrity. By mastering modern tools like version control, environment managers (Guix/Pixi), and long-term archiving via Software Heritage, you will learn how to build sustainable workflows that guarantee your science is credible, citable, and built to last.