  We review several aspects of the calculation of exoplanet model atmospheres
in the current era, with a focus on understanding the temperature-pressure
profiles of atmospheres and their emitted spectra. Most of the focus is on gas
giant planets, both under strong stellar irradiation and in isolation. The
roles of stellar irradiation, metallicity, surface gravity, C/O ratio, interior
fluxes, and cloud opacity are discussed. Connections are made to the
well-studied atmospheres of brown dwarfs as well as sub-Neptunes and
terrestrial planets, where appropriate. Illustrative examples of model
atmosphere retrievals on a thermal emission spectrum are given and connections
are made between atmospheric abundances and the predictions of planet formation
models.
