The political and legal status of Taiwan (or the Taiwan Issue, Mainland Issue or Taiwan Strait Issue as referred to by the Republic of China) hinges on whether Taiwan, Penghu, Kinmen, and Matsu should remain effectively independent as territory of the Republic of China (ROC); become unified with the territories now governed by the People's Republic of China (PRC); formally declare independence and become the Republic of Taiwan; as well as whether the existence and legal status as a state ("country") of both the ROC and the PRC is legitimate as a matter of international law, and how much diplomatic recognition either entity receives from the international community.

Currently, Taiwan, Penghu, Kinmen, Matsu, and some other minor islands effectively make up the jurisdiction of the state with the official name of Republic of China but widely known as Taiwan. The ROC, which took control of Taiwan (including Penghu and other nearby islands) in 1945, ruled mainland China and claimed sovereignty over Outer Mongolia (now Mongolia) and Tannu Uriankhai (part of which is present day Tuva, Russia) before losing the Chinese Civil War and relocating its government to Taipei, Taiwan in December 1949. On September 1951, Japan officially renounced its right to Taiwan in the Treaty of San Francisco without explicitly stating the sovereignty status of Taiwan, and hence some supporters of Taiwanese independence argue that the sovereignty of Taiwan is still held by the Allies.

Cross-Strait relations (simplified Chinese: 海峡两岸关系; traditional Chinese: 海峽兩岸關係; pinyin: Hǎixiá liǎng'àn guānxì) are the relations between mainland China and Taiwan, which are separated by the Taiwan Strait in the west Pacific Ocean, and in particular between their respective governments:

In 1949, with the Chinese Civil War turning decisively in the Communists' (CPC) favour, the ROC government led by the Kuomintang (KMT) retreated to Taipei, in Taiwan, while the CPC proclaimed the PRC government in Beijing.

Since then, the relations between China and Taiwan have been characterized by limited contact, tensions, and instability. In the early years, military conflicts continued, while diplomatically both governments competed to be the "legitimate government of China". More recently, questions around the political and legal status of Taiwan have focused on the alternative prospects of political unification with China or full Taiwanese independence. The People's Republic remains hostile to any formal declaration of independence and maintains its claim over Taiwan. At the same time, non-governmental and semi-governmental exchanges between the two sides have been increasing. From 2008, negotiations began to restore the "three links" (transportation, commerce, and communications) between the two sides, cut off since 1949. Party-to-party talks between the CPC and the KMT have resumed and semi-official negotiations through organizations representing the interests of their respective governments are being scheduled.

Coordinates: 23°30′N 121°00′E / 23.500°N 121.000°E / 23.500; 121.000

Taiwan (ⁱ/ˌtaɪˈwɑːn/; Chinese: 臺灣 or 台灣; see below), officially the Republic of China (ROC; Chinese: 中華民國; pinyin: Zhōnghuá Mínguó), is a sovereign state in East Asia. The Republic of China, originally based in mainland China, now governs the island of Taiwan, which constitutes more than 99% of its territory, as well as Penghu, Kinmen, Matsu, and other minor islands, following its loss of the mainland China territory in 1949 in the Chinese Civil War. This remaining area is also constitutionally called the "Free area of the Republic of China" which is not ruled by the Communist Party of China in Beijing.

Neighboring states include the People's Republic of China (PRC) to the west (mainland China), Japan to the east and northeast, and the Philippines to the south. Taiwan is one of the most densely populated countries in the world with a population density of 649 people per km² in October 2015.Taipei is the seat of the central government, and together with the surrounding cities of New Taipei and Keelung forms the largest metropolitan area on the island.

Taiwan Province (Chinese: 臺灣省 or 台灣省; pinyin: Táiwān Shěng; Pe̍h-ōe-jī: Tâi-oân Séng) is one of the two administrative divisions of the Republic of China (ROC) that are officially referred to as "provinces". The province covers approximately 69% of the actual-controlled territory of the ROC, with around 31% of the total population.

Geographically it covers the majority of the island of Taiwan as well as almost all of its surrounding islands, the largest of which are the Penghu archipelago, Green Island, Xiaoliuqiu Island and Orchid Island. Taiwan Province does not cover territories of the special municipalities of Kaohsiung, New Taipei, Taichung, Tainan, Taipei, and Taoyuan, all of which are located geographically within the main island of Taiwan. It also does not include the counties of Kinmen and Lienchiang, which are located alongside the southeast coast of mainland China and administered as a separate Fujian Province (not to be confused with the PRC's Fujian Province).

Taiwan (historically called Formosa, from Portuguese: Ilha Formosa, "Beautiful Island", Portuguese pronunciation: [ˌiʎɐ fuɾˈmɔzɐ]) is an island in East Asia; it is located some 180 kilometres (112 miles) off the southeastern coast of mainland China across the Taiwan Strait. It has an area of 35,883 km² (13,855 sq mi) and spans the Tropic of Cancer. The East China Sea lies to the north, the Philippine Sea to the east, the Luzon Strait directly to the south and the South China Sea to the southwest. Taiwan proper makes up 99% of the territory of the Free Area of Republic of China, after the ROC lost its mainland China territory in the Chinese Civil War and fled to the island in 1949, and the country itself is commonly referred to as simply "Taiwan".

Taiwan is a tilted fault block, characterized by the contrast between the eastern two-thirds, consisting mostly of five rugged mountain ranges parallel to the east coast, and the flat to gently rolling plains of the western third, where most of Taiwan's population reside. There are several peaks over 3,500 m, the highest being Yu Shan at 3,952 metres (12,966 ft), making Taiwan the world's fourth-highest island. The tectonic boundary that formed these ranges is still active, and the island experiences many earthquakes, a few of them highly destructive. There are also many active submarine volcanoes in the Taiwan Straits.