Recent observations of interstellar regions of the Milky Way and of nearby galaxies, by the James Webb and Euclid space telescopes, have demonstrated the wealth of information that we can currently obtain on the InterStellar Medium (ISM) and on its intricate relation with star formation. We are entering an age where the amount and complexity of the data on the ISM calls for dedicated methods for processing observations, extracting the physical information they contain and comparing them to numerical simulations.

The present summer school will address the following outstanding questions.

• What are the new methods needed to analyze the data collected by modern observatories in our field?
• Which new concepts (observations, models) are required to bridge the remaining gap in angular resolution between the Milky Way and external galaxies?
• How can we apply our knowledge of the Galactic ISM to other galaxies? What are the limitations?
• How peculiar is the ISM of the Milky Way? How representative are nearby systems to understand the cosmic evolution of galaxies?

This summer school will be the third edition of the GISM (Galaxies' ISM) series. It will center around high-level lectures covering the different aspects of this field. This year, about one third of the lectures will be devoted to presenting modern data analysis methods, and will be accompanied with a dedicated hands-on application. In parallel, each participant will work, in a small group, on a project whose results will be presented at the end of the school. Finally, there will be a few round table discussions on open questions, state-of-the-art methods and on practical aspects of careers in astrophysics.

• Dalya BARON (Carnegie Observatories, USA)
• Danielle BERG (University of Texas, Austin, USA)
• Pierre CHAINAIS (École Centrale de Lille, France)
• Emma CURTIS LAKE (University of Hertfordshire, UK)
• Emmanuel DARTOIS (ISMO, Orsay, France)
• Simon GLOVER (University of Heidelberg, Germany)
• Javier GOICOECHEA (CSIC, Madrid, Spain)
• Anna MCLEOD (Durham University, UK)
• Adeline PAIEMENT (Université de Toulon, France)
• Kate PATTLE (University College London, UK)
• Donatella ROMANO (INAF, Bologna, Italy)
• Antoine ROUEFF (Université de Toulon, France)
• Serena VITI (Leiden University, Netherlands)

• Francesco BELFIORE (INAF, Arcetri, Italy)
• Frédéric GALLIANO (AIM, CEA Paris-Saclay, France; chair)
• Annie HUGHES (IRAP, Toulouse, France)
• Chiaki KOBAYASHI (University of Hertfordshire, UK)
• Evangelia NTORMOUSI (SNS, Pisa, Italy)
• Jérôme PETY (IRAM, Grenoble, France)
• Antoine ROUEFF (Université de Toulon, France)
• Patrice THEULÉ (LAM, Marseille, France)