Harry Potter and the Half-Blood Prince is the sixth novel in J. K. Rowling's Harry Potter series. Set during Harry Potter's 6th year at Hogwarts, Voldemort is definitely back and with a vengeance. Harry finds his world is yet again changing. Wizards and witches and Muggles are dying despite the efforts of the Ministry of Magic and the Order of the Phoenix to stop them. The war is back on. Despite the danger, Harry and his best friends, Ron and Hermione, reunite and return to the familiar life of Hogwarts for their 6th year. They find yet another Defence Against the Dark Arts teacher; Professor Snape. They begin their N.E.W.T. classes in preparation for life after Hogwarts, and Harry gets some much needed Potions help from the mysterious Half-Blood Prince. Quidditch is as popular as ever, Harry is nominated Gryffindor Quidditch Captain, and he finds himself reforming his team.
As well, this book sees the introduction ever-popular Slug Club, along with the appointment of a new Potions teacher, Horace Slughorn. Romance again comes to Hogwarts, and is a welcome balance to the grim happenings elsewhere. Harry deeply questions his own feelings for Ginny Weasley, Ron's younger sister, while trying to understand the effect it is having on his friends. Yet while life at Hogwarts continues, the deaths also continue, with someone trying to bring it into Hogwarts. Danger seems to lurk around every corner, and Harry is as determined as ever to unmask it. Albus Dumbledore takes Harry under his guidance and together they explore Lord Voldemort's past, to find a way to stop him before it is too late. Ultimately, Harry finds he must accept what he must do as The Chosen One against Voldemort and choose between what is right, and what is easy.
When it was released on 16 July, 2005, it was the first book in the United Kingdom to have a simultaneous standard print, large print, and Braille edition release. Within the first 24 hours, the book sold 6.9 million copies in the U.S. alone, roughly moving 250,000 an hour, making it the fastest selling book in history. It generated more than $100 million in sales out of the gate, outpacing even the combined take of the top films at the box office. Bookseller Barnes and Noble reported sales averaging 105 copies per second in the first hour of sales.