Handkerchief is the most dominant symbol that circulates in the entire play. Handkerchief functions as a symbol of love because Othello has given it to his wife, Desdemona as a gift. Therefore, Iago uses it to play with sentiments of Othello. Since Iago knows that it symbolizes fidelity of Desdemona, so when Othello finds it in Cassio’s possession, he is convinced that his wife is not faithful. Another symbolic function of handkerchief is chastity, as Othello believes that Desdemona is chaste as long as she possesses the handkerchief, however, if she loses it, then it means she loses her virginity and chastity. It also serves as a symbol of mysterious past of Othello and his exoticness.
As English Tutor mentioned, the handkerchief is a multifaceted symbol in that it symbolizes different things to various characters. To Desdemona, the handkerchief is a symbol of Othello’s love. Iago uses the handkerchief to manipulate Othello into thinking that Desdemona has betrayed him, so to Othello, the handkerchief goes from a symbol of Desdemona’s fidelity to evidence of her infidelity.