Chinese reunification is the goal of Chinese nationalism which is the unification of Mainland China, Hong Kong, Macau, and Taiwan into a single state under a single government of China. As Hong Kong and Macau are now under the sovereignty of the People's Republic of China, the only outstanding issue is between the mainland and Taiwan.
It is supported by the government of the People's Republic of China and to varying degrees by the Kuomintang and People First Party in the Republic of China on Taiwan which are known as the pan-blue coalition. It is opposed by supporters of Taiwan independence including supporters of the Democratic Progressive Party of Taiwan and the Taiwan Solidarity Union, which are known as the pan-green coalition. Within the political scene of Taiwan, unification versus independence defines the political spectrum with the caveat that much of the support to either bloc is unrelated to the U versus I issue and with the caveat that most people in Taiwan are in the middle of the spectrum.
Chinese reunification is often stereotyped as being the ideology of the Mainlander community on Taiwan, although there are many non-Mainlanders who support reunification and many Mainlanders who oppose it. In addition, the parties which do support reunification often command considerable support for reasons that have nothing to do with cross-strait relations. Furthermore, even strong supporters of reunification often have deep reservations about the timing and nature of reunification. The PRC has proposed reunification between the mainland and Taiwan under a one country, two systems scheme similar to that of Hong Kong, but this has little support in Taiwan, even among unification supporters.
Until the mid-1970s the concept of reunification was not the main subject of discourse between the PRC and the ROC; each formally envisioned a military takeover of one by the other. The concept of unification replaced the concept of liberation by the PRC in 1979 and within Taiwan, the possibility of retaking the mainland became increasingly remote in the 1970s particularly after the death of Chiang Kai-shek.
With the loosening of authoritarian rule in the 1980s and the shift in power within the Kuomintang away from the Mainlanders who accompanied Chiang to Taiwan, the KMT began to move away from the ideology of Chinese reunification. In the 1990s, President Lee Teng-hui increased these shifts within the Kuomintang leading to confrontation with the People's Republic of China and splits within the Kuomintang.
Until the mid-1990s, supporters of Chinese reunification on Taiwan were also bitterly opposed to the Communist Party of China. Since the mid-1990s there has been a considerable warming of relations between the Communist Party and supporters of Chinese reunification. This has brought about the accusation that reunification supporters are attempting to sell out Taiwan. The standard response is that closer ties with Mainland China are in the interest of Taiwan.
After the elections of 2000 which brought the independence-leaning Democratic Progressive Party to power, the Kuomintang, faced with defections to the People First Party, expelled Lee Teng-hui and his supporters and shifted the party toward reunification. Also, the People's Republic of China has shifted its efforts at promoted reunification away from military threats (which it has not renounced but which it has not emphasized) toward economic incentives designed to encourage Taiwanese businesses into investing in the Mainland and creating a pro-Beijing bloc within the Taiwanese electorate.
Within Taiwan, supporters of reunification generally do not assert that the Republic of China should be the sole Chinese government. In addition, supporters of reunification also do not oppose localization of culture or a Taiwanese identity but rather see the Taiwanese identity as one piece of a broader Chinese identity rather than as a separate cultural identity. What supporters of Chinese reunification do oppose is desinicization or the effort to create a Taiwanese identity that is separate from the Chinese one.
See also: Political status of Taiwan