  This article provides an overview of how models of giant planet interiors are
constructed. We review measurements from past space missions that provide
constraints for the interior structure of Jupiter. We discuss typical
three-layer interior models that consist of a dense central core and an inner
metallic and an outer molecular hydrogen-helium layer. These models rely
heavily on experiments, analytical theory, and first-principle computer
simulations of hydrogen and helium to understand their behavior up to the
extreme pressures ~10 Mbar and temperatures ~10,000 K. We review the various
equations of state used in Jupiter models and compare them with shock wave
experiments. We discuss the possibility of helium rain, core erosion and double
diffusive convection may have important consequences for the structure and
evolution of giant planets. In July 2016 the Juno spacecraft entered orbit
around Jupiter, promising high-precision measurements of the gravitational
field that will allow us to test our understanding of gas giant interiors
better than ever before.
