Boston is the capital and most populous city of the Commonwealth of Massachusetts in the United States. The city proper covers 48 square miles with an estimated population of 685,094 in 2017, making it also the most populous city in New England. Boston is the seat of Suffolk County as well, although the county government was disbanded on July 1, 1999. The city is the economic and cultural anchor of a substantially larger metropolitan area known as Greater Boston, a metropolitan statistical area (MSA) home to a census-estimated 4.8 million people in 2016 and ranking as the tenth-largest such area in the country. As a combined statistical area (CSA), this wider commuting region is home to some 8.2 million people, making it the sixth-largest in the United States.

Boston is one of the oldest cities in the United States, founded on the Shawmut Peninsula in 1630 by Puritan settlers from England. It was the scene of several key events of the American Revolution, such as the Boston Massacre, the Boston Tea Party, the Battle of Bunker Hill, and the Siege of Boston. Upon gaining U.S. independence from Great Britain, it continued to be an important port and manufacturing hub as well as a center for education and culture. The city has expanded beyond the original peninsula through land reclamation and municipal annexation. Its rich history attracts many tourists, with Faneuil Hall alone drawing more than 20 million visitors per year. Boston's many firsts include the United States' first public park (Boston Common, 1634), first public or state school (Boston Latin School, 1635) and first subway system (Tremont Street Subway, 1897).

The Boston area's many colleges and universities make it an international center of higher education, including law, medicine, engineering, and business, and the city is considered to be a world leader in innovation and entrepreneurship, with nearly 2,000 startups. Boston's economic base also includes finance, professional and business services, biotechnology, information technology, and government activities. Households in the city claim the highest average rate of philanthropy in the United States; businesses and institutions rank among the top in the country for environmental sustainability and investment. The city has one of the highest costs of living in the United States as it has undergone gentrification, though it remains high on world livability rankings.