Stockholm serves as the capital and most populous city of Sweden, functioning as the largest urban area in the Nordic countries. It sits across fourteen islands where Lake Mälaren flows into the Baltic Sea, with the extensive Stockholm archipelago lying to the east along the coast. The municipality acts as the county seat for Stockholm County and holds the status of an Alpha− world city according to the GaWC classification. As the primary financial centre of Sweden, it hosts the headquarters of most major banks and numerous corporate offices in the Nordic region.

The area has been settled since the Stone Age, with written mentions of Stockholm dating to 1252 when it was founded by Swedish statesman Birger Jarl to protect against sea invasions. The name likely derives from words meaning log and islet, referring to Helgeandsholmen. Stockholm rose to prominence through Hanseatic League trade and became the de facto capital in 1436, officially designated as such in 1634 during the Swedish Empire era. It remained Sweden's political centre through various historical shifts, including the Kalmar Union and subsequent independence.

The city's character is defined by its unique geography, with over thirty percent of its area consisting of waterways and another thirty percent of green spaces. The inner city includes Gamla Stan, built on a central island from the mid-13th century, and features buildings from all ages since the 15th century. Key landmarks include Stockholm Palace, the official residence of the monarch, and Drottningholm Palace. The Stockholm metro, opened in 1950, is renowned for its station decor, often described as the longest art gallery in the world.

Stockholm is a major cultural hub hosting annual Nobel Prize ceremonies and banquets at the Stockholm Concert Hall and City Hall. It contains around seventy museums, including the Vasa Museum, which is the most visited in Scandinavia. The city is home to top-ranking universities such as the Karolinska Institute and KTH Royal Institute of Technology. It also serves as a significant tech centre, sometimes called Europe's innovation hub, and has hosted international events like the 1912 Summer Olympics.

The municipality had a population of 984,748 as of 2022, with approximately one million people living in the city proper. The Stockholm region accounts for over a third of Sweden's GDP, ranking among the top ten regions in Europe by GDP per capita. It is the hub of most Swedish rail and bus traffic, with two busy airports nearby providing access to other parts of the country. The city maintains fresh air and water quality, supported by its extensive green areas and post-glacial rebound geography.