How Does Shakespeare Use Dramatic Irony In Othello?

Throughout Shakespeare's Othello, dramatic irony is used to emphasize the cruel motivation, which has created a theme of being careful with who can be trusted. In the play dramatic irony is used in the characterization of Iago. He was exceedingly devious and had the other characters in the play believe his mendacious words and mischievous actions.
Iago's unrestrained jealousy is fueled by losing the promotion as lieutenant to michael cassio whilst similarly in the film, jago’s jealousy is driven by the loss of promotion in the police force. As a result of this “green-eyed monster”, a vivid metaphor comparing jealousy to a monster reflecting its danger as seen through the actions of Iago and Jago, where the “seed” of doubt regarding Desdemona’s fidelity was gradually ingrained. This was distinctly exhibited through the dramatic irony of I shall have reason to show the love and duty that I bear you receive it from me. I speak not yet of proof” accentuating his prominent position of power as the audience gain insight into the plot, recognising that iago does not yet have proof yet insinuates that he will somehow give him confirmation.
Iago’s continual maintenance of his personas/power of manipulation enables to gain Othello’s complete trust evident in the dramatic irony of the epithet ‘honest Iago’ which is continually used by Othello throughout the play to describe Iago. In the last scene of the play, Lodovico says “to the state this heavy act with heavy heart relate” his emotive language emphasising the significant impacts on the social landscape as a result of Iago’s deceit and manipulation. Through the notion of appearance and reality, Iago’s character propels the tragedy as he continues to deceive and maintain a veil of honesty with the other characters warning the audience of the deceitful nature of an individual driven by blind ambition.