The main source for Othello is a short story, ‘the seventh novella in the third decade’, of Giraldi Cinthio’s Hecatommithi of 1565/6.
You can also download this article about Othello and its sources.
Having read some of the source material:
How do the changes Shakespeare made affect your perceptions of the female characters?
Why might Shakespeare have made these changes?
© Royal Shakespeare Company