Wisconsin is a state in the Upper Midwest and Great Lakes regions of the United States. It borders Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michigan to the northeast, and Lake Superior to the north. With a population of about 6 million and an area of about 65,500 square miles, Wisconsin is the 20th-largest state by population and the 23rd-largest by area. It has 72 counties. The state's most populous city is Milwaukee. Its capital and second-most populous city is Madison; other urban areas include Green Bay and the Fox Cities.

Wisconsin's geography is diverse, with dense forests in the north (including Chequamegon–Nicolet National Forest), rugged unglaciated hills in the western Driftless Area, and wooded plains, lowlands, and farms stretching from the interior east to Lake Michigan. Wisconsin has the third-longest Great Lakes coastline, after Ontario and Michigan. At the time of European contact, the area was inhabited by Algonquian and Siouan nations, and today it is home to eleven federally recognized tribes. Originally part of the Northwest Territory, it was admitted as a state in 1848. During the 19th and early 20th centuries, many European settlers entered the state, mostly from Germany and Scandinavia. Wisconsin remains a center of German American and Scandinavian American culture, particularly in its cuisine, with foods such as bratwurst and kringle.

Wisconsin is one of the nation's leading dairy producers and is known as "America's Dairyland"; it is particularly famous for its cheese. The state is also famous for its breweries, with beer in Milwaukee a longstanding industry. Wisconsin has some of the nation's most permissive alcohol laws and is known for its drinking culture. Its economy is dominated by manufacturing, healthcare, information technology, and agriculture—specifically dairy, cranberries, and ginseng. Tourism is also a major contributor to its economy. The gross domestic product in 2020 was $348 billion. Wisconsin is home to one UNESCO World Heritage Site, comprising two of the most significant buildings designed by Wisconsin-born architect Frank Lloyd Wright: his studio at Taliesin and his Jacobs I House. Politically, it is considered a swing state in national and statewide elections; the Republican Party was founded in Wisconsin in 1854.

The word Wisconsin originates from the name given to the Wisconsin River by one of the Algonquian-speaking Native American groups living in the region at the time of European colonization. The French explorer Jacques Marquette was the first European to reach the Wisconsin River, arriving in 1673 and calling the river Meskousing (likely ᒣᔅᑯᐤᓯᣙ meskowsin) in his journal. Subsequent French writers changed the spelling from Meskousing to Ouisconsin, and over time this became the name for both the Wisconsin River and the surrounding lands. English speakers anglicized the spelling from Ouisconsin to Wisconsin when they began to arrive in large numbers during the early 19th century. The legislature of Wisconsin Territory made the current spelling official in 1845.

The Algonquian word for Wisconsin and its original meaning have both grown obscure. While interpretations vary, most implicate the river and the red sandstone that lines its banks. One leading theory holds that the name originated from the Miami word Meskonsing, meaning 'it lies red', a reference to the setting of the Wisconsin River as it flows through the reddish sandstone of the Wisconsin Dells. Other theories include claims that the name originated from one of a variety of Ojibwa words meaning 'red stone place', 'where the waters gather', or 'great rock'. More recently, University of Wisconsin-Green Bay lecturer and Menominee elder Napos Turney suggested the origin of the name may be the Menominee word Wēskōhsaeh, meaning "good place".

Wisconsin has been home to a wide variety of cultures over the past 14,000 years. The first people arrived around 10,000 BCE during the Wisconsin Glaciation. These early inhabitants, called Paleo-Indians, hunted now-extinct ice age animals such as the Boaz mastodon, a prehistoric mastodon skeleton unearthed along with spear points in southwest Wisconsin. After the ice age ended around 8000 BCE, people in the subsequent Archaic period lived by hunting, fishing, and gathering food from wild plants. Agricultural societies emerged gradually over the Woodland period between 1000 BCE to 1000 CE. Toward the end of this period, Wisconsin was the heartland of the "Effigy Mound culture", which built thousands of animal-shaped mounds across the landscape. Later, between 1000 and 1500 CE, the Mississippian and Oneota cultures built substantial settlements including the fortified village at Aztalan in southeast Wisconsin. The Oneota may be the ancestors of the modern Iowa and Ho-Chunk nations who shared the Wisconsin region with the Menominee at the time of European contact. Other Native American groups living in Wisconsin when Europeans first settled included the Ojibwe, Sauk, Meskwaki, Kickapoo, and Potawatomi, who migrated to Wisconsin from the east between 1500 and 1700.

The first European to visit what became Wisconsin was probably the French explorer Jean Nicolet. He canoed west from Georgian Bay through the Great Lakes in 1634, and it is traditionally assumed that he came ashore near Green Bay at Red Banks. Pierre Radisson and Médard des Groseilliers visited Green Bay again in 1654–1666 and Chequamegon Bay in 1659–1660, where they traded for fur with local Native Americans. In 1673, Jacques Marquette and Louis Jolliet became the first to record a journey on the Fox-Wisconsin Waterway all the way to the Mississippi River near Prairie du Chien. Frenchmen like Nicholas Perrot continued to ply the fur trade across Wisconsin through the 17th and 18th centuries, but the French made no permanent settlements in Wisconsin before Great Britain won control of the region following the French and Indian War in 1763. Even so, French traders continued to work in the region after the war, and some, beginning with Charles de Langlade in 1764, settled in Wisconsin permanently, rather than returning to British-controlled Canada.

The British gradually took over Wisconsin during the French and Indian War, taking control of Green Bay in 1761 and gaining control of all of Wisconsin in 1763. Like the French, the British were interested in little but the fur trade. One notable event in the fur trading industry in Wisconsin occurred in 1791, when two free African Americans set up a fur trading post among the Menominee at present-day Marinette. The first permanent settlers, mostly French Canadians, some Anglo-New Englanders and a few African American freedmen, arrived in Wisconsin while it was under British control. Charles de Langlade is generally recognized as the first settler, establishing a trading post at Green Bay in 1745, and moving there permanently in 1764. Settlement began at Prairie du Chien around 1781. The French residents at the trading post in what is now Green Bay, referred to the town as "La Baye". However, British fur traders referred to it as "Green Bay", because the water and the shore assumed green tints in early spring. The old French title was gradually dropped, and the British name of "Green Bay" eventually stuck. The region coming under British rule had virtually no adverse effect on the French residents as the British needed the cooperation of the French fur traders and the French fur traders needed the goodwill of the British. During the French occupation of the region licenses for fur trading had been issued scarcely and only to select groups of traders, whereas the British, in an effort to make as much money as possible from the region, issued licenses for fur trading freely, both to British and to French residents. The fur trade in what is now Wisconsin reached its height under British rule, and the first self-sustaining farms in the state were established as well. From 1763 to 1780, Green Bay was a prosperous community which produced its own foodstuff, built graceful cottages and held dances and festivities.