Halifax is the capital and most populous municipality of the Canadian province of Nova Scotia, and the most populous municipality in Atlantic Canada. As of 2024, it is estimated that the population of the Halifax CMA was 530,167, with 348,634 people in its urban area. The Halifax Regional Municipality (HRM) consists of four former municipalities that were amalgamated in 1996: Halifax, Dartmouth, Bedford, and Halifax County.

Halifax is an economic centre of Atlantic Canada, home to a concentration of government offices and private companies. Major employers include the Department of National Defence, Dalhousie University, Nova Scotia Health Authority, Saint Mary's University, the Halifax Shipyard, various levels of government, and the Port of Halifax. Resource industries found in rural areas of the municipality include agriculture, fishing, mining, forestry, and natural gas extraction.

The Mi'kmaq name for the harbour around which Halifax exists is Kjipuktuk or Chebookt, meaning "Chief Harbour" or "Great Harbour" in the Mi'kmaq language. Additionally, the Mi'kmaq referred to the area of the Halifax Peninsula comprising the downtown area and Point Pleasant Park as Amntu'kati, while the hillside where Halifax was established was referred to as Gooowakade, meaning "place of many pines". The area was called "Chebucto" until Halifax was established by Governor Edward Cornwallis in 1749, named in honour of George Montagu-Dunk, 2nd Earl of Halifax.

Before the mid-1700s, when a European (British) settlement was established at Halifax, the Colony of Nova Scotia had been administered from Annapolis Royal, near the Western opening of the Bay of Fundy. However, in 1749, King George II ordered Edward Cornwallis to establish Halifax as a new capital. Equipped with 13 transports and a sloop of war, Cornwallis founded the Town of Halifax on what is now known as the Halifax Peninsula, on June 21, 1749.

The establishment of Halifax marked the beginning of Father Le Loutre's War. By unilaterally establishing Halifax, the British were violating treaties with the Mi'kmaq (1726) that were signed after Father Rale's War. Cornwallis brought along 1,176 settlers and their families. To protect the new Protestant settlements from Mi'kmaq, Acadian, and French attacks, British fortifications were erected in Halifax (Citadel Hill, 1749), Bedford (Fort Sackville, 1749), Dartmouth (1750), and Lawrencetown (1754), all areas within the modern-day Municipality.

The community of St. Margaret's Bay, also in the Municipality, was first settled by French-speaking Foreign Protestants at French Village, Nova Scotia, who migrated from Lunenburg, Nova Scotia, during the American Revolution.

In the 18th and 19th centuries, Halifax grew to become a centre of government (particularly military), trade, and shipbuilding. The completion of the Intercolonial Railway in 1876 helped make Halifax a major gateway for Atlantic trade—particularly in winter, when ice made ports on the St. Lawrence River inaccessible.

This connection to trans-Atlantic trade and military enterprises bore deadly consequences on December 6, 1917. In one of the great disasters in Canadian history, the SS Mont-Blanc, a French cargo ship carrying munitions, collided with the Belgian Relief vessel SS Imo in "The Narrows" between upper Halifax Harbour and Bedford Basin. The resulting Halifax Explosion devastated the Richmond District in the North End of Halifax, killing about 2,000 people and injuring nearly 9,000 others. The blast was the largest artificial explosion before the development of nuclear weapons. Aid came from Boston, strengthening the bond between the two coastal cities.