Stony Brook University (SBU), officially the State University of New York at Stony Brook, is a public research university in Stony Brook, Long Island, in the metropolitan area of New York City. Along with the University at Buffalo, it is one of the State University of New York system's two flagship institutions.

Consisting of 213 buildings over 1,454 acres of land in Suffolk County, it is the largest public university in the state of New York by area.

The institution was opened on September 16, 1957, in Oyster Bay, as the State University College on Long Island,[1] and moved to Stony Brook in 1962.In 2001, Stony Brook was elected to the Association of American Universities, a selective group of major research universities in North America. It is also a member of the larger Universities Research Association.It is classified among "R1: Doctoral Universities – Very high research activity".

Stony Brook University, in partnership with Battelle, manages Brookhaven National Laboratory, a national laboratory of the United States Department of Energy. The university acquired land for a Research & Development Park adjacent to its main campus in 2004, and has four business incubators across the region. The University's impact on the Long Island economy amounts to US$7.23 billion in increased output, and research expenditures have surpassed the US$230 million mark annually.Stony Brook is the largest single-site employer on Long Island; 26,814 students are enrolled at the University, which has over 15,000 employees and over 2,700 faculty.