Task: Explanation
Input (English): Harry Potter and the Half-Blood Prince is the sixth and penultimate novel in the "Harry Potter" series, written by British author J. K. Rowling. Set during protagonist Harry Potter's sixth year at Hogwarts, the novel explores the past of Harry's nemesis, Lord Voldemort, and Harry's preparations for the final battle against Voldemort alongside his headmaster and mentor Albus Dumbledore. Question: Who is Harry's nemesis in the Half-Blood Prince? Answer: Lord Voldemort
Output (English):  Set during protagonist Harry Potters sixth year at Hogwarts, the novel explores the past of Harrys nemesis, Lord Voldemort, and Harrys preparations for the final battle against Voldemort alongside his headmaster and mentor Albus Dumbledore.