HAVE YOU EVER kept a diary? One of those lockable ones you hide in a secret place, so no one in your family can ever find it? The best thing about writing in a dairy, for me, was that it was never a test. No one was going to mark my spelling or grammar, and I could finish the stories when I liked - or not. Best of all, I could write about my most private thoughts, without risk of being exposed to the world. It was precisely this type of writing that made Anne Frank one of the most famous child authors in the world. Anne was just four when she and her Jewish family ran away from Nazi Germany in the 1930s to go and live in the Netherlands. At the age of 11, Anne had to go into hiding in a secret attic for two years when the Germans occupied Holland. It was during this time that she wrote The Diary Of Anne Frank. Anne's diary became one of the most widely read books in the world. Thirteen million copies have been published in more than 50 languages, so people around the world can read her story. Like Anne, 11-year-old Zlata Filipovic from Sarajevo kept a wartime diary. At first, her entries were simply about school and birthday parties, but when the Serbians invaded her country, her writing turned to stories of bombings and death. Her book was published in 1995 and is simply titled Zlata's Diary. It is a testament to the futility of war, and a poignant read in these unsettling times. While Anne and Zlata both became famous for writing about their real life experiences, other child authors have become just as famous but for different reasons. Francis Hawkins, for instance, was just eight years old when he wrote his first book in 1641. Francis is the earliest known child author, and was obviously a well-behaved (and rather serious) boy, because his book, Youth Behaviour, was all about manners and etiquette for children. The Far-Distant Oxus is another famous book written by children. Katherine Hull (then 14) and Pamela Whitlock, 15, were schoolmates in England in 1937. They were taking shelter from a rainstorm one day, when they came up with the idea of writing a book about children - by children. Their book was published a year later, and is considered a classic today. But the youngest known author must surely be American Dorothy Straight. When she was just four, she wrote How The World Began. Her parents thought her story was good enough to be published, and they were right. It went to press in 1964. Did you ever see the movie The Outsiders starring Matt Dillon and Patrick Swayze as tough teenagers who grew up on the wrong side of the tracks? This blockbuster film was based on a book written by a 15-year-old. Susan Eloise Hinton began writing The Outsiders - a book about youth gang life - in 1965. The book was published two years later, and has been assigned reading in many high schools in the United States ever since. So whether you enjoy writing about everyday life in the form of a diary, or are constantly thinking of ideas or stories, consider this: The next time you put pen to paper, who knows - you may just end up becoming the next famous child author.