What is the meaning of the symbol of prison and how is it presented throughout Hamlet?

The Ghost first uses the term in Act I, Scene 5, that he is "forbid to tell the secrets of my prison-house." Thus, the motif of the prison-house world becomes central to Hamlet's dilemma. The Ghost is trapped in the prison of purgatory as he was slain before confessing his sins. Hamlet is in a prison where everyone watches him: Claudius watches Ophelia and Hamlet, Polonious watches Hamlet as well as watching his daughter, Ophelia, and Hamlet, and Polonious also watches Gertrude and Hamlet, which leads to his death. Rosencrantz and Guildenstern are paid to watch Hamlet. Denmark becomes Hamlet's prison.

However, if you look at the prison metaphor a bit more closely, a prison must have a warden. Who keeps Hamlet confined to his prison-house world? I would suggest Hamlet, in his inability to act, becomes his own warden as well as a prisoner. Interesting thought to explore!