Queen Elizabeth has declared the London 2012 Paralympics open, during a ceremony involving more than 3,000 performers -- many of them with disabilities.
The Paralympics -- which are for athletes with a physical disability
, such as an amputation or blindness -- are held after the Olympic Games in the same host city.
The president of the International Paralympic Committee, Philip Craven, said the Games were "a celebration of the human spirit" that had "the energy to change each and every one of us."
Margaret Maughan, 84, lit the cauldron. She was Britain's first gold medal winner at the inaugural 1960 Rome Paralympics.
Earlier, athletes paraded around the Olympic Stadium.
British scientist Stephen Hawking, who has motor neuron disease and has spent most of his life in a wheelchair, played a prominent role in the ceremony, which also featured a host of deaf and disabled artists.
The ceremony signaled the start of 11 days of competition by some 4,200 athletes from more than 160 countries.
They will be competing in 20 sports, including wheelchair basketball, shooting, swimming, and track cycling.
The competition is due to run through September 9.
More than 2.4 million tickets for events have already been sold.
China finished first in the medals table at the 2008 Games in Beijing with 211 medals, followed by Britain with 102 medals.
The first Paralympic Games were held in Rome, but Britain is considered the "spiritual home" of the spectacle, as the first recognized sports competition for athletes with disabilities was held in 1948 in the English town of Stoke Mandeville.
Based on reporting by AFP and BBC