The Laser Interferometer Gravitational-wave Observatory (LIGO) and its sister project Virgo are currently acquiring data, aiming at the first direct detection of gravitational waves. These elusive ripples in the fabric of space-time, carriers of information on the acceleration of large masses, are a key prediction of General Relativity; their detection will activate a fundamental, new probe into the universe. Sources of interest for LIGO/Virgo include the coalescence of compact binary systems, core-collapse supernovae and the stochastic background from the early universe, as well as multi-messenger coincident signatures with electromagnetic or neutrino counterparts. In this talk, I will present the status of ground-based gravitational wave detectors and review the most significant observational results obtained so far. I will also outline plans for advanced detector configurations (such as Advanced LIGO) which are expected to lead to the opening of a new observational window on the universe in the coming years.