  Direct and unequivocal detection of gravitational waves represents a great
challenge of contemporary physics and astrophysics. A worldwide effort is
currently operating towards this direction, building ever sensitive detectors,
improving the modelling of gravitational wave sources and employing ever more
sophisticated and powerful data analysis techniques. In this paper we review
the current status of LIGO and Virgo ground based interferometric detectors and
some data analysis tools used in the continuous wave searches to extract the
faint gravitational signals from the interferometric noise data. Moreover we
discuss also relevant results from recent continuous wave searches.
