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Q. Do you capitalize both words in “happy birthday”?
A. Not always. To describe the act of wishing someone a happy birthday, neither term is capitalized. To name the traditional song, both words are capitalized: “Happy Birthday to You,” or “Happy Birthday.” In dialogue (as in a published novel or story), the first term would normally be capitalized at the beginning of a sentence: “Happy birthday, Rhoda!” But in a personal greeting, you can style it however you wish: Happy Birthday! 🎈🎈🎈 (birthday-themed emoji optional).