In just a few days time, the Queen will be marking 70 years since she ascended to the throne.
Her father George VI died suddenly on February 6, 1952, and she became the monarch at the age of just 25.
Throughout nearly all of her long reign, her beloved husband Prince Philip was at her side helping her to navigate life as Queen until his death aged 99 last year.
Upon marrying the then Princess Elizabeth in 1947, Philip gave up his Greek and Danish royal titles and was bestowed the title of Duke of Edinburgh.
However, he was never King - even though his wife was the Queen - and the reason for this is due to an old patriarchal system, where Kings outrank Queens.
If he had the title of King, he would have been a higher rank than the Queen - which would not have been allowed as he married into the royal family rather than being born into it.
However, the rules mean it will be a different story when Prince William becomes King one day with the Duchess of Cambridge by his side.
It's likely that Kate will become Queen Consort, and it's likely that she will opt to be Queen Catherine.
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Like Philip, as she wasn't born into the royal family she can never be Queen in her own right but she can take the 'Consort' role - which is what many wives have done in the past.
King George VI's wife became Queen Elizabeth, before becoming better known as The Queen Mother after the King's death.
Explaining the role, royal expert Marlene Koenig said: "Catherine's role will certainly change as she will be the consort of the sovereign.
"There is no real constitutional role for a consort, just by tradition.
“She will be the first lady of the land, in terms of precedence."
However, before becoming Queen, it's likely that Kate will be given yet another new title.
When Prince Charles becomes King, William will become the heir to the throne and will probably take on the title The Prince of Wales.
It is not a given that William will get the title, as it has to be bestowed upon the heir by the monarch.
However, experts predict it is more than likely that Charles will pass on his title to William.
If this happens, Kate would automatically become the Princess of Wales. The last person to hold this title was, of course, William's late mother Princess Diana. Charles's second wife, Camilla, decided against using the title out of respect for Diana.
And according to a source, if and when this is to happen, it would be an emotional moment for William.
They told the Telegraph : "I’m sure it’ll be a bit of a bittersweet moment.
"This is her son and his wife, so in some ways, it will be coming full circle—but it will also be a poignant reminder of what we all lost."
