X-rays from Star-Forming Regions in the VLT Era

The association between star-forming regions and X-ray emission was discovered over 30 years ago. We now know that essentially all young stellar objects, T Tauri stars and protostars, are X-ray emitters, although the case of the youngest, Class~0 protostars, is less clear. The paper highlights X-ray emission and absorption mechanisms, and summarizes X-ray observations of young stellar objects. The impact of the VLT on the characterization of the new X-ray sources is also briefly discussed.