X-raying the wind interactions of massive binaries. What we have learned from 25 years of observations

The collision of radiatively-driven stellar winds in massive binary systems should produce a strong X-ray emission. This emission is expected to display a phase-locked modulation due to a changing orbital separation (in eccentric systems) and/or a changing optical depth along our line of sight towards the wind interaction region. The current generation of X-ray satellites allowed the study of a number of massive binaries. They notably demonstrated that not all O + O binaries are X-ray bright and that some systems display rather complex orbital variations. In this contribution, we highlight the properties of a few systems that were recently studied with XMM-Newton.