Analysis: What's Up With the Title?
The Half-Blood Prince is a former Hogwarts student who once owned the Potions textbook that Harry adopts during his sixth year at Hogwarts. This textbook proves to be endlessly helpful as it is chock full of notes, tips, and guides about how to make successful potions. Harry spends much of his sixth year trying to understand just who this Half-Blood Prince is, and, in spite of Hermione's protestations, he keeps the book. The Half-Blood Prince helps Harry become the superstar of Potions class, a class he needs to excel at in order to fulfill his lifelong goal of becoming an Auror. However, the Half-Blood Prince also gets Harry into trouble: Harry uses an unknown spell contained in the textbook that turns out to be a dangerous piece of Dark Magic.
Why name the sixth book of the Harry Potter series after the owner of this textbook? Well, we think it has something to do with Hermione's discovery at the end of the story. By means of good sleuthing, Hermione discovers that Professor Snape's mother's maiden name was Eileen Prince, and she was a witch. Snape's father was a Muggle. Harry and Hermione come to the conclusion that Snape is the Half-Blood Prince, considering he is half-blood and he is also a Prince (by virtue of his mother's lineage). Therefore, Harry has been learning Dark Magic from the very professor he hates most. What's worse, the Half-Blood Prince turns out to be Dumbledore's killer. By the end of Book 6 we realize that we know more about Voldemort than we do about Snape. It becomes more and more clear that Harry's impending battle and journey will have much to do with the newest Professor of the Defense Against the Dark Arts: Snape.