The Queen and the Duke of Edinburgh led the country in a two-minute silence at an Armistice Day remembrance service at Westminster Abbey.
The monarch was joined by senior politicians, heads of the armed forces and former and serving military personnel for the ceremony in central London.
Prime Minister Gordon Brown and his wife Sarah were among the dignitaries at the service. The government was also represented by Defence Secretary Bob Ainsworth.
Two former prime ministers - Sir John Major and Baroness Thatcher - were at the service. Tony Blair was unable to attend because of his commitments as a Middle East envoy.
Poppies were scattered over the Tomb of the Unknown Warrior at Westminster Abbey. The Dean of Westminster, the Very Rev Dr John Hall, said the monument had become "the focus of national remembrance".
Those of all ages were involved in the 91st Armistice Day commemorations. Here people put poppies in the fountains at London's Trafalgar Square.
Scotland's rugby team, preparing for a match against Fiji on Saturday, paid their tribute at Murrayfield stadium in Edinburgh. Captain Chris Cusiter lays the wreath.
The Earl of Wessex studies the names of fallen service personnel at the national Armed Forces Memorial in Staffordshire. The monument commemorates those who have died since World War II.
Railway staff observed a two-minute silence at York station. Its normally bustling concourse was brought to a standstill at the 11th hour of the 11th day of the 11th month.
What are these?