A democratic government allows its citizens to speak their minds: a true democracy values everyone's opinion. And it is by collecting different opinions that a government can develop its nation in favour of its citizens.
However, sometimes governments intervene to prevent citizens from voicing their opinions. For example, if citizens are spreading rumours that could lead to social unrest, then a government may forbid such rumours being made public. Although social unrest is dangerous, some governments can use such fears as an excuse to censor criticism against them.
Before the arrival of the internet, the tried and tested way to speak out was to organise a protest.
In many countries, crowd actions, such as protests and union strikes, are recognised as part of the freedom of speech and are protected by law. In Hong Kong, according to Article 27 of the Basic Law, residents should enjoy freedom of speech, including the right to protest and strike.
But, if they grow out of control and threaten public safety, governments have the power to call off such protests. This helps to protect innocent members of the public if protests become riots. Yet governments can use the concern of public safety as an excuse to repress reasonable protests.
Journalists also help to maintain and fight for democracy by reporting on events using the protection of freedom of speech. They can provide the public with information about actions by governments and big business.
If journalists uncover evidence of any government or corporate wrongdoing, they are protected by law to reveal such details. Yet sometimes journalists may stumble upon sensitive information they wish to publish, such as locations of military installations and national secrets.
Journalists could be banned from revealing such information as it will pose a threat to the nation, or damage a government's reputation.
The relationship between public safety and freedom of information is complicated. There is always a struggle; a good government tries to strike a good balance between both.
Let's take a look at a few examples illustrating the conflict.
In April 1989, many Chinese students gathered in and around Tiananmen Square, in Beijing, and other cities in China, such as Shanghai and Wuhan . The peaceful demonstrations called for continued economic reform and liberalisation, and grew into a mass movement for political reform and freedom of the press.
The demonstration in Tiananmen Square was peaceful, but the central government declared martial law - claiming it had developed into a riot. On June 4, a military crackdown began, with soldiers and tanks firing on demonstrators to clear the protest. The exact number of civilian deaths is unknown as the government has never issued official figures; estimates vary from hundreds to thousands. Afterwards, foreign media were banned from entering the country.
Last September, a group of people started what became a worldwide movement at Zuccotti Park in New York, in the United States. They were protesting against investment bankers and corporate greed. They claimed that capitalism had failed, and that the world's wealth was held by the wealthy 1 per cent of the world's population, leaving the remaining 99 per cent disadvantaged.
The protest quickly spread to other cities of America - and then around the world. Protesters set up camps in the financial centres of each country to help raise people's awareness about global inequality. The demonstrations were largely peaceful, and most of people did not seem to want to inconvenience the public.
But last November 15, protesters were evicted from the park after Michael Bloomberg, New York's mayor, said the health of protesters was deteriorating and that there was concern about the safety of demonstrators sleeping there. Later, many protesters in other cities were also evicted for similar reasons.
WikiLeaks is a website created by Australian computer programmer Julian Assange. The website publishes secret information, such as official diplomatic cables and communications between departments in the American military. Although the method of acquiring the information is sometimes questionable - including the use of computer hacking - WikiLeaks has uncovered war crimes committed by American forces.
For example, the website has released documents showing injustices carried out at a detention camp in Guantanamo Bay, a US naval base in Cuba where the US army keeps its prisoners. In 2010, WikiLeaks showed a video allegedly showing an American drone attack that killed two Reuters reporters and a number of civilians.
Making such information public is seen as dangerous by the US government and many other authorities. They say Assange's website has made the job of Western troops more difficult because it has revealed their mistakes. Some of the leaked information is said to have detailed the location of American forces in the Middle East.
Assange is now fighting extradition from Britain to Sweden, to face charges of assaulting two Swedish women. But some observers say that the charges are politically motivated.
Use your own name
The internet has added a new dimension to democracy. It encourages people to speak more freely - often using anonymous blog sites and discussion forums - because they cannot be identified by name, no matter where they are.
Yet the mainland government regards the internet as a threat to public safety. It fears that if people spread damaging information on forums or mainland social website Weibo, it could lead to unrest.
To prevent that happening, Beijing recently forced internet users to use their real names. Also, it can request access to users' information from responsible websites.
This has defeated the democratic nature of the internet. Some observers fear the central government will use such efforts to fulfil its own political purposes.
Recent cases in Hong Kong
Last August, during Vice-Premier Li Keqiang's visit to the University of Hong Kong, dozens of students and alumni were kept 200m away from where the university's 100th anniversary ceremony was taking place. Up to 3,000 police were protecting Li.
Three students were reportedly pulled to the ground and one was detained inside the fire exit for an hour. Journalists later complained about the heavy-handed approach by police. But police said they had followed official guidelines.
On April 15, print and radio journalists were restricted to a far-off area when reporting on a Tiananmen story at the central government's liaison office in Wan Chai. Only four TV stations were granted a close view. Police said the decision was made owing to limited public space.
Do you know that...
Many countries allow their citizens to access information which their governments don't release publicly. The system is called freedom of information.
Depending on the country, the information can range from particular details concerning an official policy to minutes of a government meeting.
Citizens make an application stating what they wish to know. The government then determines if the information can be revealed before giving it to the applicants.
The Freedom of Information service is available in Hong Kong. A list of government departments is available for public query.