Kate announced on March 22 that she had been diagnosed with cancer.
Princess Kate's absence from the public eye, along with a photo of her with her children that was retracted due to editing, and her husband Prince William missing a royal engagement due to a "personal matter," led to rampant speculation online about Kate's well-being over the past several weeks.
Now the world knows: The 42-year-old Princess of Wales has been battling cancer.
Here is the latest on Kate's health and what is publicly known.
Kate was diagnosed with cancer that was discovered in post-operative tests after her abdominal surgery in mid-January, the princess said in a video message released March 22.
The type of cancer has not been disclosed, nor was the type of abdominal surgery Kate underwent in January.
In her video message, Kate described the operation as a "major abdominal surgery" and said that "at the time, it was thought that my condition was non-cancerous."
"The surgery was successful," Kate said. "However, tests after the operation found cancer had been present. My medical team therefore advised that I should undergo a course of preventative chemotherapy and I am now in the early stages of that treatment."
Kate shared in her message that her focus has been on her recovery, treatment, and her and William's three children, Prince George, 10, Princess Charlotte, 8, and Prince Louis, who will turn 6 in April.
"It has taken us time to explain everything to George, Charlotte and Louis in a way that is appropriate for them, and to reassure them that I am going to be OK," Kate said. "As I have said to them, I am well and getting stronger every day by focusing on the things that will help me heal, in my mind, body and spirits."
William and Kate shared a photo on their official X account on March 10, featuring Kate and their three children, Princes George and Louis and Princess Charlotte, to mark Mother's Day in the United Kingdom.
Credit for the photo — the first photo of Kate released by the palace since her hospitalization — was issued to William.
Just hours after it was released, the photo was retracted by several global news agencies over concerns it was "manipulated."
One of the agencies, The Associated Press, told ABC News in a statement it retracted the photo "because at closer inspection, it appears that the source had manipulated the image in a way that did not meet AP's photo standards. The photo shows an inconsistency in the alignment of Princess Charlotte's left hand."
On March 11, Kate issued a rare public apology, admitting to editing the photo and writing that she was sorry for any "confusion" the photo caused.
"Like many amateur photographers, I do occasionally experiment with editing," Kate said in a statement shared on X. "I wanted to express my apologies for any confusion the family photograph we shared yesterday caused. I hope everyone celebrating had a very happy Mother's Day."
Kate, whose full name is Catherine, signed the message as "C," indicating she signed off on it herself.
Hany Farid, a computer science professor at the University of California, Berkeley, told ABC News his analysis of the photo shows only "relatively minor photo manipulation."
“If you look at the sleeve of the girl on the right, you see what looks like traces of manipulation," Farid said, referring to the sleeve of Charlotte's sweater. "I think most likely it is either some bad photoshop to, for example, remove a stain on the sweater, or is the result of on-camera photo compositing that combines multiple photos together to get a photo where everyone is smiling. For the latter, if the subjects move between successive images, it can cause this type of ghosting."
Farid continued, "Either way, I think it is unlikely that this is anything more than a relatively minor photo manipulation. In addition there is no evidence that this image is entirely AI-generated.”
On Feb. 29, a palace spokesperson told ABC News that Kate was "doing well" as she continued to recover from abdominal surgery.
The spokesperson brushed off social media speculation at the time about Kate's health, telling ABC News in a statement at the time, "Kensington Palace made it clear in January the timelines of the Princess' recovery and we'd only be providing significant updates. That guidance stands."
Kate's most recent official public appearance was on Christmas Day, when she attended church with members of the royal family.
Kate was seen smiling and greeting fans as she walked to the royal family's traditional Christmas morning service at Sandringham alongside William and their three children, Princes George and Louis and Princess Charlotte.
The Waleses were joined by other members of the royal family as well, including King Charles III and his wife Queen Camilla.
Less than one month after Christmas, on Jan. 17, Kensington Palace announced that Kate had been admitted the previous day to The London Clinic for "planned abdominal surgery."
The palace did not provide further details on the type of surgery Kate underwent, but told ABC News at the time that the princess's medical issue was non-cancerous.
"The Princess of Wales appreciates the interest this statement will generate," the palace said in a statement issued on Jan. 17. "She hopes that the public will understand her desire to maintain as much normality for her children as possible; and her wish that her personal medical information remains private."
"The Princess of Wales wishes to apologise to all those concerned for the fact that she has to postpone her upcoming engagements," the statement continued. "She looks forward to reinstating as many as possible, as soon as possible."
William, the heir to the throne, postponed his public engagements while Kate was hospitalized.
He was spotted privately entering and exiting The London Clinic to visit Kate during her stay. The couple's three children are not believed to have visited Kate in the hospital.
The palace announced on Jan. 29, nearly two weeks after Kate underwent surgery, that the princess had been discharged from the hospital.
From there, Kate continued her recovery at the family's home in Windsor, about 30 miles outside of London.
"The Princess of Wales has returned home to Windsor to continue her recovery from surgery. She is making good progress," a palace spokesperson said in a statement at the time. "The Prince and Princess wish to say a huge thank you to the entire team at The London Clinic, especially the dedicated nursing staff, for the care they have provided."
The spokesperson added, "The Wales family continues to be grateful for the well wishes they have received from around the world."
Since being home from the hospital, Kate has also spent time with her family at Anmer Hall, their home in Norfolk.
After taking time off while Kate was hospitalized, William returned to his public duties on Feb. 7, stepping in for his father to lead an investiture ceremony at Windsor Castle.
Later that day, William joined actor Tom Cruise at a central London hotel for a charity fundraising gala for London's Air Ambulance.
At the gala, William made his first public remarks about Kate's health.
"I'd like to take this opportunity to say thank you, also, for the kind messages of support for Catherine and for my father, especially, in recent days," William said. "It means a great deal to us all."
Following up with a joke, William continued, "It's fair to say the past few weeks have had a rather 'medical' focus. So I thought I'd come to an air ambulance function to get away from it all."
William has since attended the BAFTAS on his own, an event at which Kate is traditionally by his side.
On Feb. 27, William sparked speculation after he missed a service of Thanksgiving for his godfather, King Constantine of Greece, at St. George's Chapel, citing a "personal matter."
William quickly returned to his public duties however, visiting the Western Marble Arch Synagogue in London later in the week.
In early March, a palace spokesperson issued a brief statement to People magazine on William's behalf in response to the online speculation around Kate's well-being,
The spokesperson said of William, "His focus is on his work and not on social media."
William's father Charles was briefly hospitalized at The London Clinic at the same time as Kate in January.
Charles stayed multiple nights at The London Clinic for a planned procedure to treat an enlarged prostate.
Shortly after he was discharged from the hospital, Buckingham Palace announced the 75-year-old king had been diagnosed with cancer.
The palace has not specified Charles's type of cancer, the stage of cancer or the type of treatment he is receiving.
In contrast to Kate, Charles has been seen publicly since his diagnosis, including attending church with Camilla in Sandringham and traveling back and forth to London for treatment.
In late February, the palace released photographs of Charles reading some of the cards and letters from well-wishes the palace says the king has received.
After Kate's cancer was announced publicly on March 22, a Buckingham Palace spokesman said in a statement that Charles was "so proud of Catherine for her courage in speaking as she did."
At the time of her surgery, the palace said Kate was not likely to resume her public duties until later this spring.
In past years, William and Kate and their children have been photographed walking to church on Easter Sunday alongside other members of the royal family.
The Wales family is now not expected to be seen publicly on Easter this year.
Kensington Palace said in a statement that Kate will return to official duties "when she is cleared to do so by her medical team."
"She is in good spirits and is focused on making a full recovery," the palace said.
The royal family is expected to gather together again publicly in June for the annual Trooping the Colour celebration for Charles' birthday.