  In this overview we discuss the prospects for a first detection of an
isotropic gravitational wave background with earth-based interferometric
detectors. Furthermore, we focus on how correlated noise sources could endanger
such a detection with current generation of detectors. Finally, we project how
correlated noise could significantly impede the potential of the future
detector, the Einstein Telescope, in its search for an isotropic gravitational
wave background. The triangular configuration of three (almost) co-located
detectors, makes the Einstein Telescope especially prone to correlated noise
sources.
