SNRs and stellar winds drive strong shock waves into the ISM and create bubbles and superbubbles filled with hot thin plasma (106–107 K), which emits soft X-ray lines and continuum emission. The ROSAT all-sky survey has revealed large structures (10 or more) in the X-ray sky, e.g., the nearby SNR Monogem Ring or the diffuse Galactic ridge emission. These structures are too large to be studied as a whole in pointed observations with today’s X-ray missions XMM-Newton or Chandra. Only the all-sky survey data from eROSITA will allow us to study the temperature, abundances, density, ionization, etc., of these large, nearby objects on 1 pc scales and to improve our understanding of the hot phase of the ISM and the nature of the observed diffuse X-ray emission. In addition, the study of X-ray shadows of dark clouds over the sky will allow us to obtain a better understanding of the local hot ISM.
