King Charles has been diagnosed with a form of cancer discovered during his recent treatment for an enlarged prostate.
Buckingham Palace says the King, 75, "remains wholly positive about his treatment" and hopes to return to full public duty "as soon as possible".
The announcement comes after more than two weeks of reports over the King's health.
Here's a timeline of what's been happening:
Buckingham Palace announces that King Charles III is set to attend hospital for treatment for an enlarged prostate the following week.
Queen Camilla says the King is "fine" and "looking forward to getting back to work" during a visit to the Aberdeen Art Gallery.
King Charles flies back from Scotland and heads to his Sandringham estate in Norfolk to rest ahead of the procedure.
King Charles's cancer diagnosis
The King meets academics from Cambridge University at Sandringham House, before travelling back to London ready for his treatment.
King Charles receives his treatment for an enlarged prostate, after being admitted to the London Clinic in the morning. Queen Camilla says of her husband: "He's doing well".
King Charles leaves hospital after three nights. Buckingham Palace says he will have to postpone his public engagements "to allow for a period of private recuperation".
Queen Camilla says her husband is "doing his best" after hospital treatment.
The King and Queen attend church in Sandringham, with Charles waving at well-wishers, in his first public outing since treatment.
Buckingham Palace announces that King Charles has been diagnosed with a form of cancer discovered during his recent treatment. The type of cancer has not been revealed, but according to a palace statement the King has started "regular treatments".
The King expresses his "heartfelt thanks" for messages of support he has received. In his own message from Sandringham House, the King said: "It is equally heartening to hear how sharing my own diagnosis has helped promote public understanding and shine a light on the work of all those organisations which support cancer patients and their families across the UK and wider world."