  Astrophysical observations reveal a large diversity of radii and masses of
exoplanets. It is important to characterize the interiors of exoplanets to
understand planetary diversity and further determine how unique, or not, Earth
is. Assessing interior structure is challenging because there are few data and
large uncertainties. Thus, for a given exoplanet a range of interior structure
models can satisfy available data. Typically, interior models aim to constrain
the radial structure and composition of the core and mantle, and additionally
ice, ocean, and gas layer if appropriate. Constraining the parameters of these
layers may also inform us about interior dynamics. However, it remains
challenging to constrain interior dynamics using interior structure models
because structure models are relatively insensitive to the thermal state of a
planet. Nevertheless, elucidating interior dynamics remains a key goal in
exoplanetology due to its role in determining surface conditions and hence
habitability. Thus far, Earth-like habitability can be excluded for
super-Earths that are in close proximity to their stars and therefore have high
surface temperatures that promote local magma oceans.
