Her advancing age and the coronavirus pandemic slowed her down in her final years, but until then Queen Elizabeth II spent decades representing the monarchy at home and abroad as Britain's official head of state.
The role meant she was responsible for "constitutional and representational duties", according to the official royal family website.
As constitutional monarch, she was strictly apolitical, and kept her hands out of the messy inner workings of government.
But she was responsible for appointing the leader of the biggest party in parliament as prime minister.
She also represented the monarchy at countless events, ceremonies and receptions during her 70-year reign.
Added to that was the regular round of honors presentations and ceremonial appearances.
She formally approved parliamentary bills into law – no royal assent has been withheld since 1708 – and confirmed official appointments.
Among her most high-profile ceremonial duties was the annual State Opening of Parliament in London.
Traditionally, although not always, she would wear the heavy Imperial Crown and an ermine cloak, setting out her government's legislative agenda from a gilded throne.
She would also hold weekly private meetings with the prime minister of the day to discuss pressing political matters, during which she could "encourage and warn".
But by convention she could not oppose decisions of her ministers. Her greatest role was "impartiality", said royal author Bob Morris.
- World traveller -
The queen was head of the armed forces, supreme governor of the Church of England, and head of the 54-nation Commonwealth.
Her many overseas trips, to the countries where she was also head of state and beyond, made her what the New York Times in 2021 called "the last global monarch".
She travelled to 117 countries during her reign, making more than 180 visits to Commonwealth countries in "soft power" diplomacy to ensure Britain's place in the world.
The Daily Telegraph newspaper estimated she clocked up enough miles to travel around the world 42 times.
She stopped travelling abroad in November 2015 at the age of 89, handing over responsibility for overseas visits to her eldest son and heir, Charles.
At home, she hosted 150 state visits during her reign, meeting world leaders, including 13 of the last 14 sitting US presidents.
As head of state, she met new ambassadors to Britain, giving them their official credentials.
- Public face -
The coronavirus pandemic curtailed the queen's ability to meet ordinary members of the public, as she self-isolated at her Windsor Castle home, west of London.
The restrictions were a contrast to the 139,000 people a year she hosted at garden parties, receptions, lunches, dinners and medal ceremonies, according to her 2020-2021 financial statement.
She also sent 293,000 congratulatory telegrams to centenarians, and 892,000 messages to couples celebrating their diamond (60th) wedding anniversary.
At Christmas, the queen was a regular on television, delivering a message to the nation and the Commonwealth for 64 years. She largely wrote it herself.
Her daily life – and year – was like clockwork, and included the study of government files sent to her in official red boxes.
Since the pandemic struck, she divided her time between Windsor and Balmoral in northeast Scotland, where she spent the summer.
Christmas and New Year were traditionally spent at Sandringham, in eastern England.