Conversation so far:
Who was the half blood prince?
Voldemort was the half-blood prince.
What is JK Rowling's book Harry Potter and the Half-Blood Prince about?
Set during 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

Question: When was the half blood prince published
Self-contained rewrite: When was JK Rowling's book Harry Potter and the Half-Blood Prince published?