Almost 2,000,000 people have liked a post Mark Zuckerberg uploaded which confirmed the birth of his second daughter.

The Facebook founder took to social media last night and shared a letter he and his wife, Priscilla Chan, had penned in honour of their newest arrival – August.

"Priscilla and I are so happy to welcome our daughter August! We wrote her a letter about the world we hope she grows up in, and also hoping she doesn't grow up too fast," the 33-year-old began.

The proud parents referred to a letter they wrote August's older sister Max upon her arrival in 2015, but said that they didn't intend to focus on the same things in this letter.

Following Max's birth, Mark and Priscilla spoke about the world they hoped their first child would grow up in, but in this latest letter they focus on childhood.

"The world can be a serious place. That's why it's important to make time to go outside and play," Mark and Priscilla wrote.

"You will be busy when you're older, so I hope you take time to smell all the flowers and put all the leaves you want in your bucket now. I hope you read your favorite Dr. Seuss books so many times you start inventing your own stories about the Vipper of Vipp."

"I hope you ride the carousel with Max until you've tamed every color horse. I hope you run as many laps around our living room and yard as you want. And then I hope you take a lot of naps. I hope you're a great sleeper. And I hope even in your dreams you can feel how much we love you."

In the letter which has been, unsurprisingly, inundated with messages of support and congratulations, Mark and Priscilla asserted: "Childhood is magical."

"You only get to be a child once, so don't spend it worrying too much about the future. You've got us for that, and we'll do everything we possibly can to make sure the world is a better place for you and all children in your generation."

Finishing the letter with a nod to the future of their family, they added: "August, we love you so much and we're so excited to go on this adventure with you. We wish you a life of joy, love and the same hope you give us."