First lady Dr. Jill Biden sent well wishes to Queen Elizabeth ahead of the monarch’s Platinum Jubilee celebrations.

The message from Dr. Biden aired exclusively Wednesday on “Good Morning America.”

“Your Majesty, Joe and I wish you a wonderful celebration of your Platinum Jubilee,” Biden said. “Congratulations on 70 years of service to the United Kingdom and Commonwealth, and thank you for your enduring friendship with the American people.”

Last year at Windsor Castle, Biden and her husband, President Joe Biden, visited Queen Elizabeth, who has met nearly every U.S. president elected during her 70-year reign.

A jubilee celebrates a significant milestone in the life and reign of a monarch.

Over the course of her 70 years on the throne, the longest reign in Britain’s history, Queen Elizabeth II has celebrated five jubilees prior to this one, her Platinum Jubilee.

In 1977, the queen celebrated her Silver Jubilee, marking 25 years on the throne. She and her husband, the late Prince Philip, marked the occasion by traveling tens of thousands of miles throughout the U.K. and the Commonwealth on jubilee tours.

Fifteen years later, in 1992, Elizabeth celebrated her Ruby Jubilee, marking her 40th anniversary as a monarch. She did not host public jubilee events that year, which she later described in a speech as “Annus Horribilis,” or “horrible year,” due to a fire at Windsor Castle and the end of three of her children’s marriages.

In 2002, Elizabeth celebrated her Golden Jubilee, marking 50 years on the throne. The queen and Philip again traveled throughout the U.K. and the Commonwealth for a celebration that culminated with a concert at Buckingham Palace.

In 2012, the queen marked her Diamond Jubilee with a boat pageant on the River Thames. The pageant featured hundreds of boats and an estimated 1 million people watching along the river.

In 2017, the queen celebrated her Sapphire Jubilee, marking 65 years on the throne, the first time a British monarch had celebrated a 65-year reign. A series of royal gun salutes commemorated the anniversary across London.

Queen Elizabeth II’s Platinum Jubilee celebration, which marks her 70th year on the throne, has its own official emoji.

Fittingly, the emoji is that of a corgi, the queen’s favorite dog breed.

Elizabeth was gifted her first corgi, Susan, by her father, King George VI, when she was 18.

The queen is believed to have owned at least 30 corgis during her 70-year reign.

During those 70 years, Elizabeth’s corgis have been seen by her side in countless photos, videos and even official portraits.

Britain’s royal family marks an historic first this week as they lead the U.K. -- and the world -- in celebrating Queen Elizabeth II’s Platinum Jubilee.

The 96-year-old queen is the first British monarch in history to reach a Platinum Jubilee, which marks 70 years on the throne. She ascended to the throne on Feb. 6, 1952, following the death of her father, King George VI.

Starting Thursday, the Platinum Jubilee celebration will include everything from the traditional Trooping the Colour birthday parade for the queen to a star-studded concert led by Diana Ross to thousands of street parties across the country.

Queen Elizabeth II shared a written thank you message on Sunday to mark the end of four days of celebrations for her Platinum Jubilee.

"When it comes to how to mark seventy years as your Queen, there is no guidebook to follow. It really is a first. But I have been humbled and deeply touched that so many people have taken to the streets to celebrate my Platinum Jubilee," Elizabeth wrote. "While I may not have attended every event in person, my heart has been with you all; and I remain committed to serving you to the best of my ability, supported by my family."

"I have been inspired by the kindness, joy and kinship that has been so evident in recent days, and I hope this renewed sense of togetherness will be felt for many years to come," the queen continued. "I thank you most sincerely for your good wishes and for the part you have all played in these happy celebrations."

The queen signed her message with her first name, Elizabeth, followed by the letter R, which stands for Regina, the Latin word for queen.