It's a Special Administrative Region of mainland China.
Let's start with something relatively easy -- with a little bit of history. After the first Opium War in 1842, Hong Kong (Hong Kong Island) became a British crown colony. It was later occupied by Japan after the Second World War and was eventually returned to the British in 1945.
After a few years, several declarations came into effect which paved the way for Hong Kong's independent features. The People's Republic of China together with United Kingdom signed the Sino-British Joint Declaration of 1985 to let Hong Kong continue the exercise of its sovereignty. In 1997, The British decided to "handover" or "return" Hong Kong back to the People's Republic of China making it a Special Administrative Region where it enjoyed the highest autonomy in China. (Or at least they said it was). Hong Kong and Mainland China always had a bittersweet relations with each other -- and it taught me a lot of things.
It's nothing like China
Even though it is technically a province of mainland China, I realized that it's nothing alike. They're completely different people bound by the same ethnic origins. Obviously, one is a communist while the other exercises limited democracy. They speak different languages/dialects. The people of Hong Kong speaks Cantonese while PRC speaks Mandarin chinese. Even from their culture to politics, they remain intrinsically divergent.
For the record, they're "one" on "some" things: military and diplomacy. Den Xiao-ping created the "one country, two systems" to provide an answer to Hong Kong. Under this doctrine, the Special Administrative Region of China is allowed to have their own set of government headed by the Chief Executive (not a President, like you thought it was), separate political system, monetary and fiscal systems, multi-party systems, legislatures and so on. Except in two things: national defense (military) and diplomatic affairs (foreign policy).
It uses it's economic power to carry out it's foreign policy
Hong Kong is an economic powerhouse and its economic prowess is deeply rooted in its location. As a less populated piece of territory in the 19th century, this entrepôt quickly blossomed into one of the most important financial hubs in the globe. While several factors come into play in determining a pivotal power in a region, (i.e. population, land mass, raw materials, climate etc) it is said that size doesn't really matter if it's strategically located in the map. According to the Global Power City Index (GPCI), most cities that doesn't possess a vast amount of raw resources and land mass, like Singapore, placed 5th on the global rankings. Many experts speculated that Singapore had a few advantages in their hands such as their location in the Southeast Asia and it proved to be their key feature to become a powerful figure in the global stage.
Like Singapore, Hong Kong remains to be a melting pot of human connections. It was a market governed by thousands of people who came across this hub decades ago -- and it continues to be this way until today. The open door policy of Den Xiao-ping created another era for Hong Kong's economy. At this point, Hong Kong could no longer depend on China's prosperity. Clearly, Hong Kong's economic growth achieved a staggering growth in its post-war industrialization stage as more immigrants, refugees and entrepreneurs flocked the city. Making it a vital part of mainland china to bolster its economic stability.
Hong Kong may not have the ability to send diplomats, independently sign treaties with other countries or send out troops to maintain geopolitical influence but it's economic power and influence is clearly understood by the world leaders as something to be given equal importance and thus becomes Hong Kong's most powerful card in the game of world affairs.
They love their umbrellas
During my trip to Kowloon, I've seen people with an umbrella stitched into almost everything. Umbrella keychains, schoolbags, notebook designs and so on. Why is it everywhere and what does it mean? In September 2014, thousands of people gathered in the streets of Mongkok in a pro-democracy protest. The People's Republic of China has reneged its promise to grant Hong Kong a universal form of suffrage by passing reforms to change Hong Kong's electoral systems. It was seen as pro-Beijing, highly-restrictive, and manipulative. As the Chinese Communist Party (CCP) pre-screening only the "loyalists" of all the candidates. It came out as plain biased to the people of Hong Kong. Second, they wanted the current Chief Executive, Leung Chun-Ying, to step down after being seen as "pro-Beijing."
The Umbrella Revolution was named after the authorities unscrupulous use of pepper-spray instead of curbing the demonstrations. The umbrella became a popular choice to shield off the clouds of tear gas and pepper spray during the course of the protest.
Many Hong Kongers believe that Beijing fears Hong Kong will elect a pro-democracy Chief Executive that will ultimately sever ties little by little from the mainland.
It's most likely to remain under Beijing -- or not
The independence of Hong Kong remains to be unclear. Until 2047, under the 50-year agreement after 1997, Beijing will continue to exercise it's political influence in Hong Kong. According to the South China Morning Post, Democratic party Executive Director, Lam Cheuk-Ting, Beijing is likely to send troops to take over should the city seek to go independent. On the other hand, experts believed that Hong Kong is too important for Beijing to use military force in case of rebellion. The West will most likely intervene if ever the mainland would resort to aggression. One could try to predict the political status of both entities in the future. On the contrary, it's almost too early to predict anything. Given that a lot of things could happen in a decade, what more for 50 years? For the meantime, it's up to the people of Hong Kong to live up to their iron-weaved will to be independent from external control and enjoy the privilege of being called a Hong Konger rather than a Chinese.