The Queen has vowed to serve as head of state, now and into the future, in a landmark speech to mark her Diamond Jubilee.
She re-affirmed a past commitment to remain the UK's sovereign, telling the nation she re-dedicated herself "to the service of our great country".
Both Houses of Parliament gave her a standing ovation after her address to MPs and peers in ancient Westminster Hall, where the Queen said: "We are reminded here of our past, of the continuity of our national story and the virtues of resilience, ingenuity and tolerance which created it.
"I have been privileged to witness some of that history and, with the support of my family, re-dedicate myself to the service of our great country and its people now and in the years to come."
Humour is said to be an integral part of the Queen's personality and the formal address included a joke about her dealings with the dozen prime ministers who have held office during her reign.
And she made light of the fact that, after Queen Victoria, she is only the second monarch to celebrate a Diamond Jubilee, and how the Duke of Edinburgh does not like receiving compliments, before praising him for being her "constant strength and guide".
Tributes were also paid to her by the Lord Speaker Baroness D'Souza and Commons Speaker John Bercow during their formal speeches.
Mr Bercow praised her for "Sixty years of stability. Sixty years of security. Sixty years of certainty. Sixty years of sacrifice. Sixty years of service."
He added: "If, as Gandhi asserted, 'the best way to find yourself is to lose yourself in the service of others', then Your Majesty must have found yourself countless times over the past decades.
"You have dedicated yourself to others."
This was the Queen's sixth address to both Houses of Parliament. She gave similar speeches in celebration of her Golden Jubilee in 2002 and Silver Jubilee 25 years earlier in 1977.
Among the guests was Prime Minister David Cameron, some members of his Cabinet, former prime ministers Tony Blair and Gordon Brown and Labour leader Ed Miliband.
To loud laughter and applause the Queen joked: "Since my accession, I have been a regular visitor to the Palace of Westminster and, at the last count, have had the pleasurable duty of treating with twelve prime ministers."
The Queen used the word "treating" in a context to mean negotiating with someone, especially an opponent.
She went on to say: "During these years as your Queen, the support of my family has, across the generations, been beyond measure."
Her comment that "Prince Philip is, I believe, well-known for declining compliments of any kind," brought laughter from the guests and she added "but throughout he has been a constant strength and guide."
The Queen also made her audience chuckle when she joked about following in the footsteps of Victoria who celebrated her Diamond Jubilee in 1897.
She said: "So, in an era when the regular, worthy rhythm of life is less eye-catching than doing something extraordinary, I am reassured that I am merely the second sovereign to celebrate a Diamond Jubilee."
During the event a Diamond Jubilee window - a gift from the members of both Houses - was unveiled.
Artist John Reyntiens created the three-panelled stained glass monument, which is based on the royal coat of arms, features up to 1,500 pieces and will be installed above Westminster Hall's north door.
The Queen thanked the peers and MPs for the present and said: "Should this beautiful window cause just a little extra colour to shine down on this ancient place, I should gladly settle for that."
The Queen has begun a national tour to mark her jubilee and said she hoped the celebrations would "be an opportunity for people to come together in a spirit of neighbourliness and celebration of their own communities".
The work of millions in the professional and voluntary services, whose efforts were for the pubic good, would also be recognised this year as would the "remarkable sacrifice and courage of our armed forces".
Members of the Royal Family have begun touring the Queen's realms to mark her Diamond Jubilee, with Prince Harry recently returning from a trip to Belize, the Bahamas and Jamaica.
The Queen added: "These overseas tours are a reminder of our close affinity with the Commonwealth, encompassing about one-third of the world's population.
"My own association with the Commonwealth has taught me that the most important contact between nations is usually contact between its peoples.
"An organisation dedicated to certain values, the Commonwealth has flourished and grown by successfully promoting and protecting that contact."