Iwo Jima, now officially romanized Iōtō (硫黄島, "Sulfur Island"), is one of the Japanese Volcano Islands, which lie south of the Bonin Islands and together with them make up the Ogasawara Archipelago. Together with the Izu Islands, they make up Japan's Nanpō Islands. Although 1,200 km (750 mi) south of Tokyo on Honshu, Iwo Jima is administered as part of the Ogasawara Subprefecture of the Tokyo Metropolitan Government.

Only 21 square kilometers (8.1 sq mi) in size, the island is still volcanic and emits sulfurous gases. The highest point of Iwo Jima is Mount Suribachi at 169 m (554 ft) high. Although likely passed by Micronesians who made their way to the Bonins to the north, Iwo Jima was largely ignored by the Spanish, Dutch, British, and Japanese until a relatively late date after its 1543 rediscovery. The Japanese eventually colonized the island, administering it as the Ioto or Iojima Village under Tokyo's jurisdiction until all civilians were forcibly evacuated to Honshu in July 1944 near the end of World War II. Because it was able to provide secure airfields within easy range of the Japanese Home Islands, Iwo Jima was not passed by like other Pacific fortresses; instead, the Battle of Iwo Jima between February 1945 and March 1945 was some of the fiercest fighting of the Pacific War, with Imperial Japan and the United States both suffering over 20,000 casualties. Joe Rosenthal's photograph of the second flagraising on Mount Suribachi has become one of the most famous examples of wartime photojournalism and an iconic American image. Following the Japanese surrender, the US military occupied Iwo Jima along with the other Nanpo Islands and the Ryukyus; Iwo Jima was returned to Japan with the Bonins in 1968.

Now technically part of the territory of the Bonins' Ogasawara Village, the island still has no permanent inhabitants except a Self-Defense Force base on its Central Field. Its soldiers, sailors, and airmen receive their own services from Ayase or Sayama but provide emergency assistance to communities on the Bonins who are still connected with the mainland only by an infrequent day-long ferry.