The UK's Prince Harry has written a book about his life. It is also about his thoughts on the death of his mother (Princess Diana), his relationship with the press, and being a royal. The book is called "Spare". The word "spare" means someone or something that only exists in case another person or thing is lost, broken, or worn out. The title "Spare" refers to the fact that Harry would only become the UK's king if his father and brother died. The book is a bestseller worldwide. It has been published in 16 languages. People waited in line for hours to buy it. In the UK, "Spare" went on sale at midnight on Sunday. One of the UK's leading bookstores, Waterstones, said "Spare" has been one of its "biggest pre-order titles for a decade".

The book is a controversial one. A member of Britain's Royal Family has never spoken so openly before. Harry said the book tells the story about why he moved his young family to the USA, and why he gave up his official royal duties. He said the UK press has continually written bad things about his wife Meghan, and reports on his life with Meghan in a negative way. "Spare" is one way for Harry to let his family know his true feelings. The 410-page memoir contains many personal stories. He writes about how he fell out with the Royal Family. He claims his brother Prince William attacked him because he wanted to marry Meghan. He also wrote about the number of Taliban fighters he killed in Afghanistan when he was a soldier.