Expelliarmus is a spell from the Harry Potter series, created by author J.K. Rowling. It is known as the Disarming Charm, primarily used to disarm an opponent by forcing them to release whatever they are holding, typically a wand. The spell is often employed in duels and combat situations, making it a popular choice among wizards and witches. Its effectiveness lies in its ability to neutralize threats without causing harm, reflecting a preference for non-lethal methods in magical confrontations.