Which Harry Potter book became the fastest-selling children’s book in history at its 2003 launch?

Harry Potter and the Order of the Phoenix became the fastest-selling children’s book in history at its 2003 launch.

The fifth Harry Potter novel was published on 21 June 2003. It sold millions of copies immediately, with retailers in several countries opening at midnight so readers could buy it as soon as the embargo ended. The release followed the earlier records set by the series’ growing international audience.

The book is the longest novel in the original series in its English editions. Its plot follows Harry’s fifth year at Hogwarts, the Ministry of Magic’s denial that Voldemort has returned, and the formation of Dumbledore’s Army. Dolores Umbridge is introduced as a major antagonist.

The title is sometimes confused with the sixth and seventh books because all three set major sales records. The Half-Blood Prince followed in 2005, while The Deathly Hallows appeared in 2007. The Order of the Phoenix was the record-setting 2003 release.