  The LIGO Scientific Collaboration and Virgo Collaboration have carried out
joint searches in LIGO and Virgo data for periodic continuous gravitational
waves. These analyses range from targeted searches for gravitational-wave
signals from known pulsars, for which precise ephemerides from radio or X-ray
observations are used in matched filters, to all-sky searches for unknown
neutron stars, including stars in binary systems. Between these extremes lie
directed searches for known stars of unknown spin frequency or for new unknown
sources at specific locations, such as near the galactic center or in globular
clusters. Recent and ongoing searches of each type will be summarized, along
with prospects for future searches using data from the Advanced LIGO and Virgo
detectors.
