1. Harry Potter and the Philosopher's Stone (1997)
2. Harry Potter and the Chamber of Secrets (1998)
3. Harry Potter and the Prisoner of Azkaban (1999)
4. Harry Potter and the Goblet of Fire (2000)
5. Harry Potter and the Order of the Phoenix (2003)
6. Harry Potter and the Half-Blood Prince (2005)
7. Harry Potter and the Deathly Hallows (2007)
There are also several companion books such as:
* Fantastic Beasts and Where to Find Them
* Quidditch Through the Ages
* The Tales of Beedle the Bard
In addition, J.K. Rowling has written short stories and plays set in the Harry Potter universe.
If you're looking for a specific type of book, please let me know!