The Harry Potter movies consist of a total of 8 parts — the last part titled Harry Potter and the Deathly Hallows is divided into two separate parts. You can watch the complete series in the following order:
Harry Potter and the Sorcerer’s Stone
Harry Potter and the Chamber of Secrets
Harry Potter and the Prisoner of Azkaban
Harry Potter and the Goblet of Fire
Harry Potter and the Order of the Phoenix
Harry Potter and the Half-Blood Prince
Harry Potter and the Deathly Hallows (Part 1)
Harry Potter and the Deathly Hallows (Part 2)