Our aim is to bring together specialists in winds from massive stars and also observers of High-Mass X-ray Binary (HMXB) systems  in order to review the state-of-the-art in observations and modelling and to develop a unified view on the physics of the stellar winds in these systems.

Massive stars are among the most important cosmic engines: they trigger the star formation and, together with low-mass stars, enrich the interstellar medium with the heavy elements but on short time scales, ultimately leading to formation of Earth-like planets and development of life.

Among the bright X-ray sources in the sky a significant number consists of a compact object accreting from the wind of such massive stars. These winds are fast, with typical terminal velocities up to 2500 km/s , dense, with mass-loss rates M >10−7 M⊙/yr , and driven by line scattering of the star’s intense continuum radiation field. Good examples are Cyg X-1/HDE 226868, the first detected stellar-mass black hole, and Vela X-1, one of the most important accreting neutron star binaries. While the basic picture has been established for decades, many details are still debated.