After his mother's death, King Charles III of Britain became the new monarch, making William, who had previously been second in line to the throne.
That means the 40-year-old William and the 36-year-old Kate, parents of three young children, will be thrust into the spotlight as the new public faces of the monarchy.
Since Harry stepped down as a senior royal and relocated to the United States two years ago, relations between William and Harry have been icy at best.
As a result of their public display of solidarity on Saturday, many people have high hopes that Harry, 37.
As the future Prince and Princess of Wales, William and Catherine will undoubtedly be in the public eye more more than before.
There remained a barrier between him and the throne until Thursday.
We've taken out that safety net."