Othello is Shakespeare's tragedy of jealousy, written around 1603. Othello, a Moorish general commanding Venice's armies, secretly marries Desdemona – and his trusted ensign Iago, passed over for promotion, sets out to destroy him. Through hints, lies and a stolen handkerchief, Iago convinces Othello that Desdemona is unfaithful to him with his lieutenant Cassio. Othello murders her in their bed; when Iago's wife Emilia exposes the plot, Othello takes his own life beside her.

Othello was written around 1603–1604 – the first recorded performance was at court in November 1604 – placing it between Hamlet and King Lear in Shakespeare's great tragic sequence. His source was a short Italian novella from Cinthio's Gli Hecatommithi (1565), which he transformed by giving the nameless ensign a name, a dazzling wit, and a void where his motive should be. The play was first printed in quarto in 1622, then in the First Folio of 1623; the two texts differ in hundreds of small readings.

Othello is a tragedy – often called Shakespeare's domestic tragedy, because unlike Hamlet or Macbeth no crown or kingdom is at stake: the battlefield is a marriage. The public war plot dissolves early (the Turkish fleet drowns in a storm before Act 2 begins), leaving the tragedy to unfold in bedrooms and corridors. That intimacy is part of why many playgoers find it the most painful of the tragedies to watch.

The play never settles it – and that seems deliberate. Iago offers motives: he was passed over for promotion in favour of Cassio, and he voices a suspicion that Othello has slept with his wife Emilia. But the motives multiply without ever convincing, and when finally caught he refuses all explanation: "Demand me nothing: what you know, you know". Samuel Taylor Coleridge (1818) famously called Iago's soliloquising "the motive-hunting of motiveless malignity" – evil hunting for reasons rather than driven by them.

Othello is a mainstay of A-Level English Literature in the UK, and appears regularly on AP English Literature (US), IB Diploma, and undergraduate syllabuses worldwide; selected scenes and speeches are also studied at GCSE and Key Stage 3. This study guide is written to support all of these levels, with modern English translation, scene-by-scene analysis, character profiles, theme guides, and key quotes.

Othello's most famous lines track its descent from confidence to catastrophe. Among the most quoted: "It is the green-eyed monster which doth mock", "She loved me for the dangers I had passed", "I am not what I am", "Put out the light, and then put out the light", "Of one that loved not wisely but too well", and "Demand me nothing: what you know, you know". Each is analysed in depth on the key quotes page.