Soliloquies are used to present a story through the medium of a play because they provide the opportunity to tell the audience specific pieces of information which cannot be revealed through normal conversation. Characters are individuals with their own complex thoughts and emotions. Not all these thoughts and emotions can be shared with others. Though drama is something public by its nature, soliloquies help to bring to light the private side of a character's personality. It is the most appropriate formula for revealing the complex thoughts in the mind of the characters.
In Othello, he gives more soliloquies to the antagonist Iago. Since Iago is a scheming villain in his deceptions, treachery, conspiracies and pretensions can best be revealed through soliloquies. It helps to show that side of the character's personality which is hidden from the other characters who are the victims of Iago's villainy.
Shakespeare gives soliloquies to complex character in order to bring out the secret feelings and plans which the character cannot share with other characters. In his work, Hamlet, Shakespeare’s title character speaks in seven soliloquies. Each soliloquy progresses the plot, exposes Hamlet's inner thoughts to the audience and helps to create an atmosphere in the play. When Hamlet speaks in these soliloquies he is always true to the self; never pretending to be mad or taking on an insincere way of talking as he does at times in dialogue with others. These soliloquies, therefore, add much to the overall content of the play Hamlet and allows Shakespeare's audience a much better understanding of the plot. Hamlet soliloquizes often thereby revealing his doubts, dilemmas, fears, anger and musings on questions of morality. Hamlet is not the acting type so the reflective or contemplative side of his personality is best brought out through his soliloquies. His 'to be or not to be is the question' is one of the most remarkable soliloquies that serves to highlight the state of indecision in which he finds himself.