Greenwich is a town in southwestern Fairfield County, Connecticut, United States. At the 2020 census, it had a population of 63,518. Greenwich is a principal community of the Bridgeport–Stamford–Norwalk–Danbury metropolitan statistical area, which comprises all of Fairfield County, and is part of the Western Connecticut Planning Region. The town is the southwesternmost municipality in both the State of Connecticut and the six-state region of New England. The town is named after Greenwich, a royal borough of London in the United Kingdom.

Fairfield County is a county in the southwestern corner of the U.S. state of Connecticut. It is the most populous county in the state and was also its fastest-growing from 2010 to 2020. As of the 2020 census, the county's population was 957,419, representing 26.6% of Connecticut's overall population. The closest to the center of the New York metropolitan area, the county contains four of the state's top 7 largest cities—Bridgeport (1st), Stamford (2nd), Norwalk (6th), and Danbury (7th)—whose combined population of 433,368 is nearly half the county's total population.