Pratas Island in the context of "Island of Taiwan"

Taiwan, officially the Republic of China (ROC), is a country in East Asia. The island of Taiwan, formerly known to Westerners as Formosa, has an area of 35,808 square kilometres (13,826 sq mi) and makes up 99% of the land under ROC control. It lies about 180 kilometres (112 mi) across the Taiwan Strait from the southeastern coast of the Mainland China. The East China Sea is 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, including the Penghu archipelago in the Taiwan Strait, Kinmen and Matsu in Fuchien near the Mainland coast, as well as Pratas and Taiping in the South China Sea.

Geologically, the main island comprises a tilted fault block, characterized by the contrast between the eastern two-thirds, consisting mostly of five rugged mountain ranges running parallel to the east coast, and the flat to gently rolling plains of the western third, where the majority of the population resides. Several peaks exceed 3,500 m in height – the highest, Yu Shan at 3,952 m (12,966 ft), makes Taiwan the world's fourth-highest island. The tectonic boundary that formed these ranges remains active, and the island experiences many earthquakes, some of them highly destructive. There are also many active submarine volcanoes in the Taiwan Straits.

The Taiwan Area, also called the Taiwan Area of the Republic of China, the free area of the Republic of China, and the "Tai-Min Area (Taiwan and Fuchien)", is a term used to refer to the territories under the effective control of the Republic of China (ROC, commonly known as "Taiwan"). It has been in official use since the Additional Articles of the Constitution of the Republic of China took effect, ending temporary anti-communist provisions on 1 May 1991. The term is also used in the 1992 Cross-Strait Act.

The area currently under the definition consists of the island groups of Taiwan, Penghu, Kinmen, Matsu and some minor islands. The collective term "Tai-Peng-Kin-Ma" is literally equivalent except that it only refers to the geographical areas of Taiwan, Penghu, Kinmen and Matsu Area, to the exclusion of Wuqiu, Dongsha Island, and Taiping Island.

The Republic of China Army (Chinese: 中華民國陸軍; pinyin: Zhōnghuá Mínguó Lùjūn) also known as the ROC Army (ROCA); colloquially the Taiwanese Army (Chinese: 台灣陸軍; pinyin: Táiwān lùjūn) by western or mainland Chinese media, or commonly referred as the National Military’s Army (Chinese: 國軍陸軍; pinyin: Guó jūn lùjūn) by local Taiwanese people, is the largest branch of Taiwan's military, the Republic of China Armed Forces.

An estimated 80% of the ROCA is based on the Main Island of Taiwan, while the remainder are stationed on the Penghu, Kinmen, Matsu, Dongsha, and Taiping Islands. This branch was also referred to historically as the Chinese Army and the Nationalist Chinese Army during and after World War II and the 1949 retreat.

The nine-dash line, also referred to as the eleven-dash line by Taiwan, is a set of line segments on various maps that accompanied the claims of the People's Republic of China (PRC, "Mainland China") and the Republic of China (ROC, "Taiwan") in the South China Sea.

The contested area includes the Paracel Islands, the Spratly Islands, the Pratas Island and the Vereker Banks, the Macclesfield Bank, and the Scarborough Shoal. Certain places have undergone land reclamation by the PRC, ROC, and Vietnam. The People's Daily of the PRC uses the term Duànxùxiàn (Tuan-hsü-hsien; 断续线) or Nánhǎi Duànxùxiàn (Nan-hai tuan-hsü-hsien; 南海断续线; lit. 'South Sea intermittent line'), while the ROC government uses the term Shíyīduàn xiàn (Shih-i-tuan hsien; 十一段線; lit. 'eleven-segment line').