Some of the most common spells used in the Harry Potter series are Accio, Alohomora, Lumos, Avada Kedavra, and Wingardium Leviosa. Author J. K. Rowling derived the names of spells from classical languages, especially Latin, although none are grammatically correct.
MTV writer Kevin Sullivan voted Accio the most useful spell. Known as the summoning charm, it is used to propel an object through the air toward the wizard when needed. It was first used in "Harry Potter and the Goblet of Fire," when Harry summoned his broom during the Triwizard Tournament.
Alohomora is a common charm that unlocks doors. This spell first appears in "Harry Potter and the Philosopher's Stone." That book also features a famous scene in which Hermione Grainger is practicing Wingardium Leviosa, the charm used to levitate objects.
"Harry Potter and the Chamber of Secrets" introduces the Lumos charm, which creates a point of light at the end of the caster's magic wand, allowing it to function as a flashlight. The spell to extinguish the light is called Nox.
In later books, Rowling introduced curses like Crucio, which is used to cause pain, and Avada Kedavra, the killing curse.
The fictional spells of the Harry Potter lexicon are primarily categorized as charms and curses, although there are spells to conjure objects and effects, as well as ones to perform transformations. Spells usually require a gesture of the character's magic wand, along with a verbal incantation.