Taiwan, officially the Republic of China (ROC), is an island country in East Asia. The main island of Taiwan, known historically in English as Formosa, makes up 99% of the area controlled by the ROC, measuring and lying some across the Taiwan Strait from the southeastern coast of mainland China. The East China Sea lies to the north of the island, the Philippine Sea to its east, the Luzon Strait directly to its south and the South China Sea to its southwest. The ROC also controls a number of smaller islands: some in the Taiwan Strait (including the Penghu archipelago and the Kinmen and Matsu Islands near the Chinese mainland coast), and some of the South China Sea Islands.