Brandenburg is one of the sixteen states of Germany. It lies in the east of the country and is one of the new federal states that were re-created in 1990 upon the reunification of the former West Germany and East Germany. The capital is Potsdam. Brandenburg surrounds but does not include the national capital Berlin.

Historically, Brandenburg was an independent state, the Margraviate of Brandenburg, which grew to become the core of independent Prussia and later the German state of Prussia. About a third of historic Brandenburg (land east of the Oder River) was awarded to Poland after the establishment of the new Oder-Neisse border in 1945 by the Allies. This region was historically known as East Brandenburg. The federal state of Brandenburg is named after the town of Brandenburg an der Havel.

Brandenburg is bordered by Mecklenburg-Vorpommern in the north, Poland in the east, the Freistaat Sachsen in the south, Saxony-Anhalt in the west, and Lower Saxony in the northwest.

The Oder River forms a part of the eastern border, the Elbe River a portion of the western border. The main rivers in the state itself are the Spree and the Havel. In the southeast, there is a wetlands region called the Spreewald; it is the northernmost part of Lusatia, where the Sorbs, a Slavic people, still live. These areas are bilingual, i.e., German and Sorbian are both used.

Protected areas
Brandenburg is known for its well-preserved natural environment and its ambitious natural protection policies which began in the 1990s. 15 large protected areas were designated following Germany's reunification. Each of them is provided with state-financed administration and a park ranger staff, who guide visitors and work to ensure nature conservation. Most protected areas have visitor centers.

National parks

• Lower Oder Valley National Park (106 km²)

Biosphere reserves

• Spreewald Biosphere Reserve (474 km2/183 sq mi)
• Schorfheide-Chorin Biosphere Reserve (1.291 km2/0.50 sq mi)
• River Landscape Elbe-Brandenburg Biosphere Reserve (533 km2/206 sq mi)

Nature parks

• Barnim Nature Park (750 km2/290 sq mi)
• Dahme-Heideseen Nature Park (594 km2/229 sq mi)
• High Fläming Nature Park (827 km2/319 sq mi)
• Märkische Schweiz Nature Park (204 km2/79 sq mi)
• Niederlausitzer Heidelandschaft Nature Park (490 km2/189 sq mi)
• Niederlausitzer Landrücken Nature Park (580 km2/224 sq mi)
• Nuthe-Nieplitz Nature Park (623 km2/241 sq mi)
• Schlaube Valley Nature Parke (225 km2/87 sq mi)
• Uckermark Lakes Nature Park (895 km2/346 sq mi)
• Westhavelland Nature Park (1.315 km2/0.51 sq mi)
• Stechlin-Ruppiner Land Nature Park (1.080 km2/0.42 sq mi)