Othello kills Desdemona by strangling her in her bed. This is the most common way that Othello kills Desdemona, and it is also the most gruesome method of murder. Strangling someone is a painful way to die, and it can take several minutes for someone to lose consciousness. During that time, they’ll have no control over their body and will be unable to breathe or move.
Desdemona’s death is confirmed by Cassio, who says: “There’s a dead butcher on your highness’ pillow.” This indicates that she was killed in her sleep, which would mean that if Desdemona were awake when Othello strangled her, she would have fought back and tried to escape before dying from lack of air or blood loss from broken vessels in her neck.
However, it’s possible that Othello did not kill Desdemona with his hands but instead used something else such as a belt or rope as leverage while choking her until she passed out from lack of oxygen flow through her windpipe. If this were true then there would be no bruises around Desdemona.