High-resolution radio observations of X-ray binaries

I present an overview of important results obtained using high-resolution very long baseline interferometry (VLBI) observations of X-ray binary systems. These results derive from both astrometric observations and resolved imaging of sources, from black holes to neutron star and even white dwarf systems. I outline a number of upcoming developments in instrumentation, both new facilities and ongoing upgrades to existing VLBI instruments, and I conclude by identifying a number of important areas of investigation where VLBI will be crucial in advancing our understanding of X-ray binaries.