In late August, the Chinese legislature's standing committee ruled that it would not allow open nominations in Hong Kong's 2017 election for chief executive. Instead, potential candidates must be endorsed by a special nominating body in Beijing before securing a spot on the ballot.
That decision prompted small demonstrations that have since snowballed into what some are calling unprecedented protests in the city.
"I think there's fear ... on the part of the authorities, that this is just the beginning of what could become escalating protests," says Susan J. Henders, a York University political science associate professor who has studied Hong Kong's political development.
Who are the protesters?
The protests started shortly after the Chinese government's decision in August. Some university and high school students organized a week-long boycott of their classes. Many have continued their absences after the initial week.
Some students escalated the action and stormed Civic Square, which houses Hong Kong’s central government offices, on Hong Kong Island on the evening of Sept. 26.
Dubbed Occupy Central for Love and Peace, the organization piggy-backed on the students' momentum by encouraging Hong Kong residents to join a mass sit-in at Civic Square in Admiralty this past weekend. Thousands of protesters have joined the sit-in since it started.
While the movement began as a youth-led initiative, over the weekend it has grown to include other demographics.
What are their demands?
The protesters want fully democratic elections when they cast their ballots for the next chief executive.
CY Leung currently holds the position and presides over Hong Kong with assistance from the executive council. A special election committee, made up of more than 1,000 members, elected Leung. The Central People's Government of China then appointed him.
Hong Kong's 2017 election will be the first time residents vote for their chief executive.
However, protesters were dismayed to learn that the election committee will pre-approve two to three candidates from which the residents will choose a leader. The new chief executive will then still have to be appointed by the Chinese government.
The protesters want open nominations for the upcoming election.
Occupy Central also demanded that Leung's administration resume public consultation on political reform, but has since shifted to calling for the chief executive's resignation.
What is Beijing's role in Hong Kong's government?
Britain handed control of Hong Kong, one of its former colonies, to China in 1997.
The two governments negotiated a so-called "one country, two systems" method of government that ensures Hong Kong remains free of China's socialism. Hong Kong's basic law promises its capitalist system will remain untouched for 50 years.
Under the law, Hong Kong remains semi-autonomous. Despite China's involvement in Hong Kong's chief executive selection, the "ultimate aim" is for the position to be filled "by universal suffrage," according to the basic law.
Many say Beijing is now backtracking on that promise.
How has the government responded?
Part of what makes this protest so unusual is the Hong Kong police force's reaction, explains Henders.
"It's very unusual for the Hong Kong police to react with such force, in particular the fairly extensive use of tear gas," she says.
On Sunday, police responded to protesters attempting to push past cordons and barricades by employing 87 rounds of tear gas, the Associated Press reported.
The police said they needed to use force and tear gas "to stop those acts which endangered public safety and public order," according to a statement.
There are unconfirmed reports police have also used rubber bullets in an attempt to manage the crowds.
The protesters' use of umbrellas — among other equipment — to shield themselves from the potential pain of tear gas and rubber bullets has helped earned the movement the name the "umbrella revolution."
The strong showing could be an attempt to intimidate people, says Henders, with police hoping it will prevent the protests from gaining strength in numbers.
However, on Monday, police seemed to shift their tactics with officers showing more restraint.
What happens next?
"Things are at an impasse," says Henders.
The Chinese government is unwilling to negotiate on details important to the pro-democracy movement, Henders explains, while Leung has indicated he wants to extend public consultation.
Those participating in the mass sit-in have made it clear they're unwilling to back down, with leaders of Occupy Central suggesting they're willing to be arrested for their non-violent protests.
Still, the movement may not have much support from Hong Kong residents, says Henders. Despite supporting democratic development, many people in Hong Kong fear the financial repercussions of political instability, she says. They may not support the movement's tactics of camping out in the city's financial district.
Yet support for the pro-democracy movement is growing outside of Hong Kong, with solidarity demonstrations popping up in Australia, Canada and the U.S.
It will be interesting to see how the global reaction impacts the outcome of Hong Kong's protests, she says.