The Duchess of Edinburgh – formerly the Countess of Wessex – is married to the Queen's son, Prince Edward.
She is mother to Lady Louise and James, Viscount Severn.
Prior to her marriage in 1999, Sophie Rhys-Jones was head of her own public relations firm.
Since the royal wedding at Windsor Castle, Sophie has become one of the hardest working members of the British monarchy.
She and Prince Edward are even busier of late, following the departure of Prince Harry and Meghan as senior working royals.
Sophie is one of the most fashionable members of the royal family and has developed a love of British designers including Emilia Wickstead and Suzannah.
Continue through to see some of Sophie's best looks over the years.
The Duke and Duchess of Edinburgh stepped in for King Charles at a parade marking 120 years of the Entente Cordiale, a series of agreements signed by France and the United Kingdom in 1904.
In London, the ceremony was watched by Sophie and Edward, both of who filled in for King Charles, who is undergoing cancer treatment.
Sophie, 59, wore a chic pale blue dress and cream coat for the occasion.
The event marked the first time a country from outside the Commonwealth has taken part in the Changing of the Guard on the forecourt of Buckingham Palace.
Sophie and Edward have dutifully stepped up their public duties in the wake of Charles and Kate's cancer diagnoses.
It's been a huge changefor the popular royal couple, who have been promoted to undertake more senior engagements during this time.
During the Easter Mattins Service at St George's Chapel in March 2024, Sophie opted for a royal purple look – with a stylish buttoned coat and grey headpiece.
Sophie, Duchess of Edinburgh once again proved she is one of the most stylish royals in Britain after rocking this slate coloured outfit to the 2024 Commonwealth Day Service at Westminster Abbey on March 11, 2024.
The Duchess of Edinburgh attended a private screening of Rhino Man in London in June 2023, wearing a stunning floral purple gown.
Sophie, Duchess of Edinburgh, attended the Commonwealth Day at Westminster Abbey on March 13 2023.
The duchess wore a pair of earrings first seen at her wedding in 1999.
They feature white and Tahitian pearls that were made to match a necklace featuring a large cross, reportedly designed by Sophie's husband Prince Edward.
Sophie's cream suit is by Proenza Schouler.
On March 10, 2023, Prince Edward and Sophie visited Edinburgh for the first time under their new titles, to mark one year since the city's formal response to the invasion of Ukraine.
Earlier that day, the couple was given new titles by King Charles III.
They are now known as the Duke and Duchess of Edinburgh, a step up from their previous titles of Earl and Countess of Wessex.
The monarch conferred his late father's title the Duke of Edinburgh on his brother Prince Edward on his 59th birthday.
Sophie, the former Countess of Wessex, is now the Duchess of Edinburgh and their 15-year-old son James, Viscount Severn is the new Earl of Wessex.
Buckingham Palace said in a statement: "His Majesty The King has been pleased to confer the Dukedom of Edinburgh upon the Prince Edward, on the occasion of HRH's 59th birthday today.
"The title will be held for HRH's lifetime. The dukedom was last created for Prince Philip in 1947, upon his marriage to Princess Elizabeth, who held the title of Duchess of Edinburgh before acceding to the throne in 1952.
"The new Duke and Duchess of Edinburgh are proud to continue Prince Philip's legacy of promoting opportunities for young people of all backgrounds to reach their full potential."
The dukedom is not hereditary and will not pass down to the Edinburghs' son James when Edward dies.
The Countess of Wessex has had a busy start to 2023.
On January 19 – the day before her birthday on January 20 – Sophie was in Surrey to carry out three engagements.
One was at the Connaught School where the 58-year-old helped staff and students celebrate its 60th anniversary.
She even met the school's dog, Toffee.
Sophie kept warm in the UK's bitter cold with a coat by Max Mara, retailing for around $1600.
On Christmas Day in 2022, the Countess of Wessex cut a stylish figure as she joined the King and Queen Consort, and other members of the royal family, for morning mass inside St Mary Magdalene's church in Norfolk.
Sophie dressed in a coat by Joseph, wore a hat by by Jane Taylor and carried a clutch by Sophie Habsburg.
For the Royal Variety Performance at the Royal Albert Hall on December 1, 2022 the Countess of Wessex wore a gown by Erdem.
If the gown looks familiar, that's because the shorter version has been worn by two other royal ladies.
In 2016, Norway's Crown Princess Mette-Marit wore the frock in Canada and in 2017, it was seen on the then-Duchess of Cambridge, at a Buckingham Palace reception.
The Countess of Wessex wore her aquamarine tiara to a State Banquet held at Buckingham Palace on November 22, 2022.
Sophie wore a jumpsuit by British label Suzannah.
Sophie, Countess of Wessex, wore a bespoke blue lace shirt dress by Suzannah London for her appearance at day two of Royal Ascot on June 15, 2022.
Her hat is by Jane Taylor Millinery.
The countess also wore her emerald-cut aquamarine Art Deco-style brooch. The stunning jewel is surrounded by diamonds and has been worn to previous days at the races.
Many royal fans quickly pointed out the similarities between this look and the blue Elie Saab dress worn by Kate, the Duchess of Cambridge, to the same event in 2019.
The Countess of Wessex was a guest of the Royal Enclosure at day one of Royal Ascot on Tuesday June 14.
Sophie wore a custom-made rose pink frock by Suzannah London and a hat by Jane Taylor Millinery.
She accessorised with a pearl brooch and matching pearl earrings.
For Trooping the Colour on June 2, 2022, Sophie, the Countess of Wessex, wore a pink and white chequered suit by Suzannah, a favourite designer of hers, and hat by Jane Taylor.
For the Service of Thanksgiving at St Paul's Cathedral Sophie wore a rose-gold coloured dress by Suzannah.
The dress featured a tie at the back.
Her hat is by Jane Taylor and clutch by Sophie Habsburg.
The Countess of Wessex has chosen a blue floral flock for a visit with well wishers on a walkabout while attending celebrations marking the Platinum Jubilee of Britain's Queen Elizabeth on June 4.
Sophie accessorised with floral earrings and a sycamore leaf necklace.
The ankle-length dress was teamed with matching blue shoes.
Sophie, the Countess of Wessex, has led the charge showcasing her family's stylish choices at Platinum Party at the Palace, in front of Buckingham Palace on June 04.
Sophie, 57, chose a fun, white frock by Zara complete with long sleeves and waist tie.
Her son James chose a blue day suit with white shirt and Lady Louise dressed in a grey frock with matching scarf and coat.
The Earl and Countess of Wessex have wrapped up their tour of the Caribbean, in celebration of Queen Elizabeth's Platinum Jubilee.
Over seven days the couple visited Saint Lucia, Saint Vincent and the Grenadines, and Antigua and Barbuda, from April 22 until April 28.
Here, the countess visits Pigeon Island on April 28, in Saint Lucia.