Colour and color are the same word. Neither one is a mistake. Colour is the spelling used in the UK, Canada and Australia. Color is the spelling used in the United States.
First, how do you say it?
KUL-er
The word sounds the same in both spellings. The only difference is the U.
The weird part
Look at some other word pairs:
colour / color
favourite / favorite
neighbour / neighbor
honour / honor
In each pair, one spelling has an extra U. The words sound the same, but they are spelled differently on each side of the Atlantic.
Where did the difference come from?
The word comes from the Latin color. English learned it from Latin and French, and for a long time both spellings were used in different places.
Before the year 1828, words like humour and humor both appeared in writing on both sides of the Atlantic. Then an American, Noah Webster, published a big dictionary in 1828. He liked shorter, simpler spellings, and in his dictionary he chose color and similar forms. He also wanted American spelling to look different from British spelling.
His dictionary helped to make color the American standard. Some of his other changes did not spread. The British kept colour, and Canada and Australia mostly kept it too.
The reveal
Colour and color are twins. They came from the same word, and one dictionary helped to split the spelling in two. Neither one is wrong.
⚠️ Common Mistakes
Choose one and stay with it. Do not mix the two spellings in one text.
❌ My favorite colour is blue.
✅ My favourite colour is blue. / My favorite color is blue.
Match the spelling to your reader. British schools expect colour, and American schools expect color.
❌ (A US school test) The colour of the sky is blue.
✅ (A US school test) The color of the sky is blue.
Do not drop the U in other words by accident.
❌ neighbor (in a British text)
✅ neighbour (in a British text)
💬 In a Conversation
Leo: Is it color or colour?
Mia: Yes.
Leo: That's not an answer.
Mia: Both are right. The U is just on holiday.
⏳ The OddLingo Timeline
Latin "color" → both spellings in use in Britain and America → Webster's dictionary of 1828 chooses "color" → "color" in the USA → "colour" in the UK, Canada and Australia
🥡 The OddLingo Takeaway
Colour and color are both correct.
Pick the one that matches where you live or where your reader lives, and use it every time.