The rules of courtship in Othello involved keeping a relationship secret, using others to communicate between lovers, giving small gifts as tokens of affection, and giving a more special gift as a secret symbol of engagement. Many of the courtship rules in the time in which Othello was written were offshoots of older medieval traditions.
Much about these courtship rules was intended to protect the reputations of everyone involved. If Othello publicly responded to Desdemona's apparent attraction, he risked both making her father angry and making himself look foolish if Desdemona ended up denying him. This is why individuals such as Michael Cassio are used: they could send and receive messages for both parties, allowing Othello and Desdemona to be certain of their mutual attraction. Individuals such as Cassio would also bear small gifts that these secret lovers wished to exchange with one another. When the relationship had become very serious, the rules of courtship dictated that the gifts became more serious, culminating in a gift that served as a secret symbol of engagement. While this gift was traditionally a blue garter, Othello's gift to Desdemona was a handkerchief. Othello was obsessed with the handkerchief because it represented the secret love they shared. Other courtship rules included the lady's maid of honor serving as witness to both the engagement and any sex that came afterward, helping to hold the man accountable if he should try to break the engagement, especially if his lady was pregnant.