What is the definition of upstaging in drama?

In drama, upstaging refers to an actor moving or positioning themselves in a way that draws the audience's attention away from the main focus of the scene. It can be intentional or unintentional and is often considered a breach of theatrical etiquette. By blocking the view of another actor or taking focus away from a crucial moment in the scene, upstaging can disrupt the flow and impact of the performance. Directors generally plan blocking during rehearsals to avoid these situations and ensure that all actors have equal opportunities to shine.