Japan comprises over 3,000 islands, the largest of which are Honshū, Hokkaidō, Kyūshū and Shikoku, together accounting for 97% of land area. Most of the islands are mountainous, many volcanic; for example, Japan’s highest peak, Mount Fuji, is a volcano. Japan has the world's tenth largest population, with about 128 million people. The Greater Tokyo Area, which includes the capital city of Tokyo and several surrounding prefectures, is the largest metropolitan area in the world, with over 30 million residents.

Archaeological research indicates that people were living on the islands of Japan as early as the Upper Paleolithic period. The first written mention of Japan begins with brief appearances in Chinese history texts from the first century AD.

Influence from the outside world followed by long periods of isolation has characterized Japan's history. Since adopting its constitution in 1947, Japan has maintained a unitary constitutional monarchy with an emperor and an elected parliament, the Diet.

A major economic power, Japan has the world's second largest economy by nominal GDP. It is a member of the United Nations, G8, G4 and APEC, with the world's fifth largest defense budget. It is also the world's fourth largest exporter and sixth largest importer and a world leader in technology and machinery.