How Does Iago Manipulate Othello?

In Shakespeare’s play, lago plays on Othello's personal insecurities to bring about his downfall. Othello is notably an outcast, being the only black man in a white society. Throughout the whole play, he is referred to as “The Moor'. His skin color results in unfavorable preset assumptions and prompts the association of savage animalistic characteristics. Even more so, his relationship with Desdemona is in a period when such a marriage would be rare and controversial. As a result of society's prejudice, Othello's self-esteem diminishes, allowing lago to capitalize on his insecurity to invoke the feeling of jealousy in Othello.
To start off, lago insinuates that Desdemona is unfaithful to Othello, as she prefers only people of her 'type', a class Othello will never belong to. lago convincingly states, “As, to be bold with you,/ Not to affect many proposed matches/ Of her own clime, complexion, and degree,/ Whereto we see in all things nature tends”. Using this logic, lago claims that Desdemona would prefer Cassio, who is like her in age, race, and class, as opposed to Othello who is older, black and unattractive.
Similarly, lago uses Desdemona's gender and past to convince Othello of her infidelity. lago states: 'She did deceive her father, marrying you,/ And when she seemed to shake and fear your looks,/ She loved them most'. He suggests that Desdemona, having betrayed her father, is very likely to betray Othello. Combined with the knowledge that women of that time period were unvirtuous and unfaithful, this tips Othello over the edge. Piece by piece, lago wears down Othello's layers and places a heavy cloud of doubt and jealousy around him.
Furthermore, lago muddles with Othello's mind to such an extent that Othello believes no one but Iago. He cocoons Othello in a coat of lies, using his doubt and jealousy to turn him against Desdemona. Othello states: 'Oh, damn her, damn her!/ Come, go with me apart. I will withdraw/ To furnish me with some swift means of death/ For the fair devil. Now art thou my lieutenant”. Undoubtedly, Othello shapes a realm of truth from lago's lies and promotes Iago to his desired position as lieutenant. Ironically, Othello accepts lago's lies and believes them to be the truth, but believes Desdemona's truthful pleas to be a lie.
In essence, lago takes advantage of Othello's self-doubt to cradle him in a deceitful environment, and 'dehumanizes the noble general, making him into a brute against his own wife'. Thus, Iago toys with Othello's mind by using his insecurity against him.