The 2012 Summer Olympics, formally the Games of the XXX Olympiad and commonly known as London 2012, was a major international multi-sport event celebrated in the tradition of the Olympic Games, as governed by the International Olympic Committee (IOC). It took place in London, United Kingdom and to a lesser extent across the country from 25 July to 12 August 2012. The first event, the group stage in women's football began on 25 July at the Millennium Stadium in Cardiff, followed by the opening ceremonies on 27 July. More than 10,000 athletes from 204 National Olympic Committees (NOCs) participated.
Following a bid headed by former Olympic champion Sebastian Coe and then-Mayor of London Ken Livingstone, London was selected as the host city on 6 July 2005 during the 117th IOC Session in Singapore, defeating bids from Moscow, New York City, Madrid and Paris. London was the first city to host the modern Olympic Games three times, having previously done so in 1908 and in 1948.
Construction for the Games involved considerable redevelopment, with an emphasis on sustainability. The main focus was a new 200-hectare (490-acre) Olympic Park, constructed on a former industrial site at Stratford, East London. The Games also made use of venues that already existed before the bid.
The Games received widespread acclaim for their organisation, with the volunteers, the British military and public enthusiasm praised particularly highly. The opening ceremony, directed by Danny Boyle, received widespread acclaim throughout the world, particular praise from the British public and a minority of widely ranging criticisms from some social media sites. During the Games, Michael Phelps became the most decorated Olympic athlete of all time, winning his 22nd medal. Saudi Arabia, Qatar and Brunei entered female athletes for the first time, so that every currently eligible country has sent a female competitor to at least one Olympic Games. Women's boxing was included for the first time, thus the Games became the first at which every sport had female competitors.
These were the final Olympic Games under the IOC presidency of Jacques Rogge.