What is the damned spot Lady Macbeth refer to?

In William Shakespeare's play "Macbeth," the "damned spot" Lady Macbeth refers to is a metaphorical stain on her conscience that she cannot wash away. It symbolizes her guilt and remorse for her role in Duncan's murder. Despite attempting to wash her hands, she feels the spot remains, driving her further into madness and despair. The spot represents the psychological toll of committing such a heinous crime and highlights the consequences of their actions. It serves as a haunting reminder of their guilt and the inescapable burden of their deeds.