Gravitational waves are likely to bring a revolution in our understanding of the universe and new insights into the nature and dynamics of gravity, space and time. Current experimental work is focused on laying the foundations for gravitational wave searches with a sensitivity that allows to detect waves from some types of astrophysical sources, but by no means guaranteed. The second generation of detectors will carry out searches with an amplitude sensitivity 10 to 20 times higher. A third generation of detectors with even better sensitivity is now in discussion and conceptual design, involving ideas such as squeezed light, non-classical interferometers, matter waves, cooling, optical springs, and quantum non-demolition measurements. This is such a complex and difficult task, that specialists in various fields must work closely together.