Blocking search engines, charging the earth for internet, torturing activists to get their Facebook and Twitter passwords, passing laws that control what people can (and can’t) talk about online. These are just some of the ways in which nations from China to Syria, Cuba to Azerbaijan are preventing journalists, bloggers and activists from speaking out about human rights abuses.

In some countries, criticising authorities online is so dangerous that, according to Reporters without Borders, 2011 was the deadliest year for online activists - with several 'netizens' killed in Bahrain, Mexico, India and Syria.

To mark World Press Freedom Day today, we’re featuring the stories of just four of hundreds of bloggers and journalists who put their safety on the line to speak out for what they believe in.

Dina Meza | Honduras

Dina Mezo

Dina Meza reports on human rights issues for the website Defenders Online. She is also a human rights activist with the Committee of the Families of the Detained and Disappeared (COFADEH). In relation to her work on the land conflict in the Lower Aguan region of Honduras, she has received a series of calls threatening her with sexual violence.

"Censorship and self-censorship are now the inseparable companions of every journalist... If I keep quiet, impunity wins," said Dina. Check out a longer personal reflection by Dina on her work.

Since the 2009 coup d’etat in Honduras, 20 journalists have been killed. The files on these deaths carry on gathering dust in the drawers of the Public Prosecutor’s Office, impunity tries to silence a story which was never told.

Emin Milli | Azerbaijan

Emim Milli

Emin Milli a blogger and activist who used online networking tools to spread information about the socio-political situation in Azerbaijan, was arrested on 8 July 2009. He and a fellow blogger were attacked by two unidentified men in a restaurant in Baku. When they reported the incident to the police Milli and his colleague were held and charged with "hooliganism".

Azerbaijan lurched onto the international stage last year, having won the right to host Eurovision this year and having been elected a non-permanent member of the UN Security Council. The county’s government has been pumping millions of dollars of oil profit into a PR campaign portraying the nation as modern, progressive and democratic -- yet the pre-Eurovision crackdown on freedom of expression by the Azerbaijani authorities continues unabated.

Ashkan Delanvar | Iran

Ashkan Delanvar

Ashkan Delanvar, a student banned from further education for his political views, arrested in July 2010 and sentenced in June 2011 in the first case recorded by Amnesty International where an individual was sentenced to prison under the Law on Cyber Crimes for providing anti-filter software and training people in how to use it.

In January this year, Iranian authorities announced that a new Cyber Police was now working throughout the country to confront Internet crimes and counter social networks that spread "espionage and riots". They’ve since forced owners of Internet cafes to install CCTV and to register the identity of users before allowing them to use computers.

Luis Felipe Rojas | Cuba

Luis Felipe Rojas

Every time Journalist and blogger Luis Felipe Rojas wants to access the internet, he has to travel 200 kilometres from his hometown of Holguin, in eastern Cuba, to the closest cybercafé. Once there, he has to pay six US dollars to use the internet for sixty minutes - almost half a monthly local salary.

Some days he finds websites containing information considered critical of the government are blocked or messages have disappeared from his inbox.

Luis Felipe told us:

"The authorities attack us because we talk about the issues people face - that not everybody has enough food, that public services do not always work, that there are problems with the health service... Fear does not stop me. I do not think a tweet from me is going to save anybody from prison but it does save them from impunity."

Unfortunately, these four stories are just the tip of the iceberg. Journalists working in traditional media outlets from Pakistan to Colombia, Mexico to Sudan plus most nations across Eastern Europe and the Middle East face harassment, attacks, unfair imprisonment or even death just for doing their job.

Check out our complete global overview on attacks against journalists around the world.