2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/6271To underscore the value of high spectral resolution for the study of low-z QSO absorption lines, we briefly present Space Telescope Imaging Spectrograph echelle data that demonstrate how increased resolution leads to dramatic improvement in line measurements. We show that even R = lambda/Delta lambda = 20,000 is insufficient for some measurements. The higher the resolution the better, but R ~ 50,000 is adequate for many outstanding questions about the IGM and the ISM of galaxies that can be probed using QSO absorption lines.Contribution to "Hubble's Science Legacy: Future Optical-Ultraviolet Astronomy from Space"Astrophysicstext