The seismic study of the Sun and other stars offers a unique window into the
interior of these stars. Thanks to helioseismology, we know the structure of
the Sun to admirable precision. In fact, our knowledge is good enough to use
the Sun as a laboratory. We have also been able to study the dynamics of the
Sun in great detail. Helioseismic data also allow us to probe the changes that
take place in the Sun as solar activity waxes and wanes. The seismic study of
stars other than the Sun is a fairly new endeavour, but we are making great
strides in this field. In this review I discuss some of the techniques used in
helioseismic analyses and the results obtained using those techniques. In this
review I focus on results obtained with global helioseismology, i.e., the study
of the Sun using its normal modes of oscillation. I also briefly touch upon
asteroseismology, the seismic study of stars other than the Sun, and discuss
how seismic data of others stars are interpreted.Comment: To appear in Living Reviews of Solar Physic