Schleswig-Holstein is the northernmost of the sixteen states of Germany, comprising most of the two historical duchies of Schleswig and Holstein. Its capital city is Kiel, other notable cities are Lübeck, Flensburg and Neumünster.

Schleswig-Holstein borders Denmark (Region Syddanmark) to the north, the North Sea to the west, the Baltic Sea to the east, and the German states of Lower Saxony, Hamburg, and Mecklenburg-Vorpommern to the south.

The former English name was Sleswick-Holsatia, the Danish name is Slesvig-Holsten, the Low German name is Sleswig-Holsteen, and the North Frisian name is Slaswik-Holstiinj. Historically, the name can also refer to a larger region, containing both present-day Schleswig-Holstein and the former South Jutland County (Northern Schleswig) in Denmark.