  In addition to well-known mechanisms of excitation of solar and stellar
oscillations by turbulent convection and instabilities, the oscillations can be
excited by an impulsive localized force caused by the energy release in solar
and stellar flares. Such oscillations have been observed on the Sun
(`sunquakes'), and created a lot of interesting discussions about physical
mechanisms of the impulsive excitation and their relationship to the flare
physics. The observation and theory have shown that most of a sunquake's energy
is released in high-degree, high-frequency p modes. In addition, there have
been reports on helioseismic observations of low-degree modes excited by strong
solar flares. Much more powerful flares observed on other stars can cause
`starquakes' of substantially higher amplitude. Observations of such
oscillations can provide new asteroseismic information and also constraints on
mechanisms of stellar flares. The basic properties of sunquakes and initial
attempts to detect flare-excited oscillations in Kepler short-cadence data are
discussed.
