Brown Dwarfs from the Stellar Perspective

In this paper, we review the current theory of very low mass stars model atmospheres including the coolest known M~dwarfs, M~subdwarfs, and brown dwarfs, i.e. T${}_{eff}\le 5,000$K and $-2.0\le [M\mathrm{/}H]\le +0.0$. We discuss ongoing efforts to incorporate molecular and grain opacities in cool stellar spectra, as well as the latest progress in deriving the effective temperature scale of M~dwarfs. We also present the latest results of the models related to the search for brown dwarfs.