  An enigmatic prediction of Einstein's general theory of relativity is
gravitational waves. With the observed decay in the orbit of the Hulse-Taylor
binary pulsar agreeing within a fraction of a percent with the theoretically
computed decay from Einstein's theory, the existence of gravitational waves was
firmly established. Currently there is a worldwide effort to detect
gravitational waves with interferometric gravitational wave observatories or
detectors and several such detectors have been built or being built. The
initial detectors have reached their design sensitivities and now the effort is
on to construct advanced detectors which are expected to detect gravitational
waves from astrophysical sources. The era of gravitational wave astronomy has
arrived. This article describes the worldwide effort which includes the effort
on the Indian front - the IndIGO project -, the principle underlying
interferometric detectors both on ground and in space, the principal noise
sources that plague such detectors, the astrophysical sources of gravitational
waves that one expects to detect by these detectors and some glimpse of the
data analysis methods involved in extracting the very weak gravitational wave
signals from detector noise.
