Ignorance and disinformation are powerful weapons in the hands of oppressors, even more powerful than guns and batons. Knowledge sets you free, and knowledge necessarily passes through (or at least should pass through) journalism.

"Everyone has the right to freedom of opinion and expression, including the right not to be harassed for their opinions and the right to seek, receive and impart information and ideas through any media and regardless of frontiers." So reads Article 19 of the Universal Declaration of Human Rights.

To commemorate this right and pay tribute to press freedom, the United Nations, at the 1993 General Assembly, proclaimed 3 May World Press Freedom Day.

"Quality journalism allows citizens to make informed decisions about the development of their society. It is also a tool for bringing injustice, corruption and the abuse of power into the public eye. For this reason, journalism must be able to thrive in a favourable, independent and safe environment, free from undue interference," declared UN Secretary-General Ban Ki-moon, Unesco Director-General Irina Bokova and Zeid Ra'ad Al Hussein, UN High Commissioner for Human Rights.

The aim of the day is to celebrate the fundamental principles of press freedom, to assess the state of press freedom around the world, to defend the media against attacks on their independence, and to pay tribute to journalists who have lost their lives in the line of duty. Over the past ten years, more than 600 journalists have been killed; moreover, according to UN estimates, nine out of every ten murders of a journalist go unpunished.

The theme chosen by Unesco, the United Nations agency responsible for promoting and protecting press freedom worldwide, for the 2015 edition is "Let journalism thrive!".

This year's ambassador appointed by Unesco is British CNN journalist Christiane Amanpour.

The official celebrations of World Press Freedom Day 2016 were held in Helsinki. The hashtag is #WPFD2016. The Finnish capital hosted a Unesco conference on access to information and fundamental freedoms, with particular reference to freedom of information and sustainable development, and to online censorship.