On 30 June the 25th anniversary of Hong Kong's return was celebrated in China and emphasized on the OCTS(One Nation, Two System) owing to which Hong Kong is under its control. Before understanding the system we need to understand the history of Hong Kong and Macau. However, the OCTS was originally brought to merge Taiwan in China but Taiwan refused to do that, and afterward, China used the same technique to incorporate Hongkong and Macau in its territories.
So the story begins with the acquisition of Hong Kong by Britain after the first opium war in the year 1842. In 1898 China signed a convention with Britain in which it was said that the Hongkong would be on lease under the British Empire for 99 years and as far as it is concerned with Macau since 1557 Macau had been under the Colonial rule of Portuguese. In the 1980s China initiated talks with Britain and Portugal both to hand over Hong Kong and Macau to China respectively and those efforts went fruitful because Britain gave up its authority from Hong Kong in on 30 June 1997 and the Portuguese handed over Macau in1999.
Present Scenario:
Under this policy of China, OCTS, they rendered that Hong Kong and Macau can have different Political, Economic, and Legal systems and they can have their own currencies, however, that will be considered under the mainland of China. Both the regions, therefore, are deemed as the Special Administrative Regions of China. Although Hongkong and Macau have their own significant systems to govern but in the matter of Defence and Foreign Affairs, China has supreme authority. Hong Kong has freedom of assembly and expression and some democratic rights which is not possessed by the Chinese people of the mainland of China because it is a Strong Communist Country. This is possible because of the Basic Law that is the mini-constitution which describes the relation between Hong Kong and China, but that is valid only for 50 years till 2247 for Hong Kong and till 2249 for Macau. And none is sure what will be of Hong Kong and Macau with China.