The Devonian strata in New York State were the standard section for North America for over 100 years, and remain a significant reference for regional to global correlation and research. Since publication of L. V. Rickard’s (1975) New York Devonian correlation chart, various higher-resolution stratigraphic analyses have been employed, sometimes at bed-by-bed scale. These include sequence-, bio-, event-, chemo-, and other -stratigraphic approaches, along with increasingly finer-resolution geochronologic dating of airfall volcanic tephras. Results have led to many new interpretations and insights of the succession. The purpose of this three-volume work is to produce a new Devonian stratigraphic synthesis for New York State, and to record, often in detail, current knowledge of the succession, and various other geologic and paleontologic aspects of it for current and future research and discussion. The purpose of this chapter is to provide overviews of the Devonian Period, the Devonian of North America (“Laurentia”), the Devonian of eastern Laurentia, and the Devonian of New York State. Furthermore, this review extends beyond the sedimentary rock and paleobiological record, and beyond the United States, Canada, and northern Mexico, to also summarize aspects of Devonian orogenesis, metasedimentary foreland basin fill, silicic igneous activity, complexities of terranes of Mexico and Central America, and Appalachian faunas that extended into South America.