Queen Elizabeth died at age 96 on Thursday.

Her son, King Charles III, announced a period of royal mourning.

World leaders paid tribute to the Queen and Buckingham Palace opened a digital condolence book.

King Charles III announces period of royal mourning after Queen Elizabeth II dies aged 96

Queen Elizabeth II dies: What happens over the next 10 days

D-Day+1: The morning after Queen Elizabeth's death, Charles will be sworn in as the new sovereign by the Accession Council.

D-Day+2: The queen's coffin will be carried to Buckingham Palace.

D-Day+3 to D-Day+5: Charles will receive the motion of condolence at Westminster Hall and later start his tour of the United Kingdom as its new monarch.

D-Day+6 to D-Day+9: Queen Elizabeth II will lie in state at Westminster Hall in the Palace of Westminster for three days in what is being called Operation Feather. For 23 hours per day, visitors will be able to pay their respects. Tickets will be issued to VIPs for designated time slots.

Charles will travel to Wales to receive another motion of condolence and attend a service at Llandaff Cathedral in Cardiff ahead of the queen's funeral, which will take place the following day.