In November 2011, President Ali Abdullah Saleh handed over power to his deputy, Abdrabbuh Mansour Hadi, following months of anti-government protests and hundreds of deaths.
Demonstrations calling for the end of Mr Saleh's 33-year rule began at the end of January 2011, with tens of thousands taking to the streets of the capital, Sanaa.
The president quickly announced that he would not seek re-election in 2013 and would not pass power to his son, but the promise failed to end the protests. As they became more frequent and widespread, security forces and supporters of the president launched a deadly crackdown.
In late April 2011, Mr Saleh's General People's Congress (GPC) party agreed to a Gulf Co-operation Council-brokered deal to hand over power in return for immunity from prosecution, but the president refused to sign. The decision prompted the head of the powerful Hashid tribal federation, Sheikh Sadiq al-Ahmar, to declare his support for the opposition.
Heavy fighting between security forces and armed tribesmen subsequently erupted in Sanaa, leaving dozens of people dead. In June 2011, Mr Saleh was seriously injured by a bomb explosion inside the presidential compound in the capital. He was forced to travel to Saudi Arabia, and then to the United States, to receive medical treatment.
Many Yemenis thought the attack would see Mr Saleh finally step down from power, but in September he returned to presidential palace amid a new wave of violence.
In October 2011, the UN Security Council again urged the president to agree to the GCC-brokered deal, but it was not until 23 November that he signed. Mr Hadi assumed presidential powers until 25 February 2012, when he was sworn in as head of state following an election in which he was the only candidate. Mr Saleh formally ceded power two days later.
President Hadi is expected to serve a two-year term to pave the way for new parliamentary and presidential elections in 2014.
In that time, he must tackle widespread poverty and malnutrition, a secessionist movement in the south, and Islamist militants linked to al-Qaeda in the Arabian Peninsula who took advantage of the instability to temporarily seize control of several southern towns.
Many Yemenis are also angry that Mr Saleh, his family and his supporters will not be prosecuted for the deaths of people during the uprising.