Honor is a central concept or theme in Shakespeare's Hamlet.
Honor is defined as...
...honesty, fairness, or integrity in one's beliefs and actions
Hamlet is an honorable man. When he learns that his father has been murdered, he is ready to avenge Old Hamlet's death, as a loyal son would do. However, he is not certain at first that the Ghost is actually that of his father or an evil spirit trying to win his soul to eternal damnation (a common belief in Shakespeare's time). While some argue that Hamlet's delay in carrying out his revenge is Hamlet's flaw and results in the deaths of almost everyone in the play, I disagree. The Elizabethan audience would have understood that killing a king (regicide) was a mortal sin. If Hamlet is going to proceed, he must be fairly certain that the Ghost is an "honest" one. This seems a wise course of action in my mind, especially when one's soul rests in the balance.
Hamlet continues to endeavor to find proof of Claudius' death. Hamlet arranged to have visiting players (actors) re-enact his father's murder, in the presence of Claudius (Old Hamlet's brother and murderer). If Claudius reacts in a guilty way, Hamlet will have his proof and will kill him. In Act Two, scene two, Hamlet declares that he will watch Claudius closely. If the King even turns pale by watching the murder in the play, Hamlet will know what needs to be done next. He also notes that the Ghost may be a trick by the devil to destroy Hamlet, who is especially susceptible because of his deep depression. So Hamlet will watch Claudius for proof, and he plans to use the play to expose this proof.
I'll tent him to the quick. If he but blench,
I know my course. The spirit that I have seen
May be a devil; and the devil hath power
T' assume a pleasing shape; yea, and perhaps
Out of my weakness and my melancholy,
As he is very potent with such spirits,
Abuses me to damn me. I'll have grounds
More relative than this. The play's the thing
Wherein I'll catch the conscience of the King. (II.ii.592-600)
Honor is attacked in several ways. Polonius has sold his honor to Claudius in order to be more closely tied to the king, and to feel self-important. There is some question as to Gertrude's sense of honor when she not only remarries so quickly after her husband's death, but also that she marries her brother-in-law.
Claudius dishonors Danish crown because he stole it—through murder.
Laertes, like Hamlet, has lost his father. However, rather than behave honorably (as Hamlet is trying to do in his situation), Laertes joins Claudius in secret, to attack and murder Hamlet out of revenge for Polonius' death, while pretending to meet Hamlet with reconciliation in his heart.
Honor is attacked as Laertes accuses Hamlet of murdering Polonius, never considering that it might have been an accident, etc.
As Laertes listens, Claudius says he cannot kill Hamlet because of Hamlet's mother's love for him, and because Hamlet is a favorite with the Danish subjects. In order to incite Laertes to dispose of Hamlet for him, Claudius asks Laertes:
What would you undertake
To show yourself your father's son in deed
More than in words? (IV.vii.135-137)
Laertes quickly responds in a blasphemous tone.
To cut his throat i' the church.
So Claudius asks what Laertes would be willing to do to avenge Polonius' death; Laertes promises that he would even kill Hamlet in a church.
The two most important examples of the presentation and attack of honor in the play can be found in Hamlet's sincere desire to take revenge for his father's death only if he finds proof to show his actions are honorable. By comparison Laertes attacks Hamlet's honor by letting his anger get the best of him and listening to Claudius' lies, driving Laertes to not only question Hamlet's honor, but also to turn his back on his own honor.