Mr Assange ran Wikileaks, a website that published many confidential or restricted official reports related to war, spying and corruption.
In 2010, it released a video from a US military helicopter which showed civilians being killed in the Iraqi capital Baghdad.
It also published thousands of confidential documents supplied by former US Army intelligence analyst Chelsea Manning. These suggested that the US military had killed hundreds of civilians in unreported incidents during the war in Afghanistan.
The revelations became a huge story, prompting reaction from all corners of the globe, and led to intense scrutiny of American involvement in foreign conflicts.
The US said the leaks had endangered the lives of American personnel.
Mr Assange was accused of conspiring to break into its military databases, external to acquire sensitive information, and was charged with 18 offences.
Efforts were made to bring him to the US for prosecution – which he fought for 14 years in some of the world’s highest courts.
Mr Assange has always argued that he exposed serious abuses by US armed forces, and that the case against him was politically-motivated.
