The Observational View.

Within less than two decades, the study of low-mass stars and brown dwarfs has bloomed into one of the most active fields in astronomy. The M, L, T and Y dwarfs sequences includes objects spawning more than an order of magnitude in absolute temperature, from 4000 K down to room temperature, and nearly fills the entire temperature gap between the coolest stars and our Solar System’s giant planets. I present an overview of the large-scale surveys that led to the discovery of a population of ultracool dwarfs in our immediate galactic vicinity, their classification and various noteworthy spectroscopic features found only in these objects. I provide an outline of photometric variability study of L and T dwarfs, which opens a unique window on the atmospheric phenomenon at play in their atmospheres. Finally, I summarize the capabilities of an upcoming instrument, the SPIRou near-infrared, high-resolution spectropolarimeter, that will be available to the CFHT communities in 2015. SPIRou will be a unique tool for the study of cool dwarfs, and will be used to undertake an ambitious survey of habitable Earth-sized planets around nearby M dwarfs. [ABSTRACT FROM PUBLISHER]