  Solid body tides provide key information on the interior structure,
evolution, and origin of the planetary bodies. Our Solar system harbours a very
diverse population of planetary bodies, including those composed of rock, ice,
gas, or a mixture of all. While a rich arsenal of geophysical methods has been
developed over several years to infer knowledge about the interior of the
Earth, the inventory of tools to investigate the interiors of other
Solar-system bodies remains limited. With seismic data only available for the
Earth, the Moon, and Mars, geodetic measurements, including the observation of
the tidal response, have become especially valuable and therefore, has played
an important role in understanding the interior and history of several Solar
system bodies. To use tidal response measurements as a means to obtain
constraints on the interior structure of planetary bodies, appropriate
understanding of the viscoelastic reaction of the materials from which the
planets are formed is needed. Here, we review the fundamental aspects of the
tidal modeling and the information on the present-day interior properties and
evolution of several planets and moons based on studying their tidal response.
We begin with an outline of the theory of viscoelasticity and tidal response.
Next, we proceed by discussing the information on the tidal response and the
inferred structure of Mercury, Venus, Mars and its moons, the Moon, and the
largest satellites of giant planets, obtained from the analysis of the data
that has been provided by space missions. We also summarise the upcoming
possibilities offered by the currently planned missions.
