Is colour the correct spelling?

Colour with a U is the correct spelling in British English and in many other forms of English outside the United States, while color without a U is the correct spelling in American English. Both are correct, but their correctness depends on regional standard and audience. Colour is the standard spelling in the United Kingdom, Ireland, Australia, New Zealand, Canada, South Africa, and other Commonwealth countries, and is listed as the preferred spelling in the Oxford English Dictionary. Color is the standard spelling in the United States and is preferred by American dictionaries like Merriam-Webster and style guides like AP Stylebook and Chicago Manual of Style. The difference comes from early 19th century spelling reforms by American lexicographer Noah Webster, who simplified many British spellings ending in our to or, such as colour to color, flavour to flavor, honour to honor, and labour to labor, to create a distinct American English identity. If you are writing for a British, Australian, or Canadian audience or following British style guides, colour is correct. If you are writing for an American audience, color is correct. In international contexts, either is understood, but you should be consistent within a document.