A charm is A spell that augments the person or object on which the spell is cast. It aims to change what the object does, rather than change what it is.
Charms are found throughout the wizarding world, and at Hogwarts School of Witchcraft and Wizardry they are taught starting in students’ first year. Charms exist for a variety of purposes, from amplifying sound to water-making. Due to the definition of a charm, curses, jinxes, and hexes are all considered charms and are referred to by the wizarding world as “dark charms”