Profile: Saudi Arabia's Crown Prince Mohammed bin Salman
Few people outside Saudi Arabia had heard of Prince Mohammed bin Salman before his father became king in 2015. But since then, the 31-year-old has become the most influential figure in the world's leading oil exporter.
He has now been elevated to the position of crown prince, replacing his cousin Mohammed bin Nayef - a move that had been widely expected and could shape the direction of the country for decades.
Mohammed bin Salman was born on 31 August 1985, the eldest son of then-Prince Salman bin Abdul Aziz Al Saud's third wife, Fahdah bint Falah bin Sultan.
After gaining a bachelor's degree in law at King Saud University in the capital Riyadh, he worked for several state bodies. In 2009, he was appointed special adviser to his father, who was serving as governor of Riyadh at the time.
Mohammed bin Salman's rise to power began in 2013, when he was named head of the Crown Prince's Court, with the rank of minister. The previous year, Salman had been appointed crown prince after the death of Nayef bin Abdul Aziz - the father of Mohammed bin Nayef.
In January 2015, King Abdullah bin Abdul Aziz died and Salman acceded to the throne at the age of 79.
He immediately made two decisions that surprised observers, naming his son minister of defence and Mohammed bin Nayef deputy crown prince. The latter became the first of the grandsons of Ibn Saud, the founder of the kingdom, to move on to the line of succession.
One of Mohammed bin Salman's first acts as defence minister was to launch a military campaign in Yemen in March 2015 along with other Arab states after President Abdrabbuh Mansour Hadi was forced into exile by the Houthi rebel movement.
The campaign has made limited progress over the past two years, seen Saudi Arabia and its allies being accused of human rights violations, and triggered a humanitarian crisis in the Arab world's poorest country.
In April 2015, King Salman made more startling changes to the line of succession, appointing Mohammed bin Nayef as crown prince and his son deputy crown prince, second deputy prime minister and president of the Council of Economic and Development Affairs.
Since then, Prince Mohammed bin Salman has unveiled his wide-ranging plan to bring social and economic change in the oil-dependent kingdom, Vision 2030.
He has also overseen the reduction of the country's lavish subsidies and proposed the partial privatisation of the state oil company, Saudi Aramco.
Mohammed bin Salman has also represented King Salman abroad, travelling to Beijing, Moscow and Washington, where he met President Donald Trump in March.