Dialogue is the correct word for a conversation, whether in everyday speech, a book, a film, or peace talks between nations. Dialog is an uncommon variant spelling, but it lives on in computing, where a dialog box is the small window that pops up asking you to confirm or choose something.
The core difference
Dialogue covers conversation and discussion in general use; dialog is mainly reserved for the computing term dialog box.
- dialogue — conversation between people, especially in writing: She wrote sharp, funny dialogue for the sitcom.
- dialogue — a formal exchange between groups: The two nations agreed to open a dialogue on trade issues.
- dialog — short for dialog box, or an uncommon spelling of dialogue: A dialog popped up asking her to save the file.
How to tell them apart
Both words share the same root: dialogue comes from Old French dialoge, from Greek dialogos, built from dia- ('through, between') and legein ('to speak'). Dialog is simply a variant spelling of the same word, formed the same way American English trims other -logue words.
The reliable way to choose is by context rather than nationality. For conversation, writing, or diplomacy, dialogue is the word to reach for almost everywhere, including in American publishing. Dialog survives mainly as computing shorthand — a dialog box, or the ellipsis 'dialog' on its own — so if you're not talking about software, dialogue is very likely the spelling you want.
