Guards Francisco and Bernardo tell Horatio, a friend of Hamlet, about the ghost they had seen that resembles Hamlet's father. They convince Horatio to join them and attempt to talk with the ghost if it reappears. Horatio scoffs at the talk of a ghost but agrees to wait. As they begin describing what they saw, the ghost appears.
The scene opens with King Claudius celebrating his recent wedding to Gertrude in a bright castle room surrounded by courtiers. An unhappy Hamlet sits outside the action. It is two months since his father's death and his widow has already married his brother.
Polonius lectures his son on how to conduct himself at school, advising him to treat his friends well, listen more than talk, dress well but not too well, avoid lending money, and "to thine own self be true." Then he warns Ophelia about Hamlet. She promises not to see him.