Sophie married Prince Edward at Windsor Castle after six years of dating.
The couple have since had two children together, Lady Louise Windsor, 16, and James, Viscount Severn, 12.
When she married Prince Edward, Sophie swapped her career in Public Relations to become a working royal.
Like all full time members of the Royal Family, Sophie will regularly appear alongside the Queen at official events.
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Are Sophie, Countess of Wessex and the Queen friends?
Sophie has been pictures with her mother-in-law many times during the past 20 years.
Analysing snaps of them together, body language expert Judi James gave a glimpse into their relationship.
She told Express.co.uk: “The Queen’s body language with Sophie always suggests her daughter-in-law is a bit of a confidante.
“Sophie’s relaxed, constantly calm and upbeat demeanour seems to allow the Queen to relax more in her company, too.”
Sophie and the Queen’s body language shows the two royal are comfortable in each other’s company.
The pair may have formed a close bond due to their shared interest of activities such as horse riding.
Sophie and Lady Louise live nearby the Queen in Windsor and have regularly been spotted riding together.
No matter what the reason, the royals seem to get on very well, with Sophie considered a favourite of her mother-in-law.
A royal aide told Mail Online: “She is trusted and relied on by the Queen in a way I couldn’t say applied to the Duchess of Cambridge or the Duchess of Cornwall.
“She is like another daughter to Her Majesty, they are that close.”