开心

Using it is incredibly simple. You usually put 很 (hěn) before it to say "very happy." In Chinese, we rarely just say "I am happy" without a modifier. You say 我很开心. You can also use it to describe an event. If a party was great, you say 玩得很开心. It acts like an adjective or a result of an action. Just don't use it for "happy birthday"—that is a different word!

Use it whenever you feel a spark of joy. Use it when meeting a friend for coffee. Use it when you get a nice text message. It is perfect for social media captions under a smiling selfie. If you are at a dinner party, tell the host you are 开心. It shows you are genuinely enjoying their company. It is a warm, high-energy word for everyday life.

Do not use 开心 for deep, philosophical happiness. For that, use 幸福 (xìngfú). Also, avoid it in very somber or overly professional documents. It is a bit too "bubbly" for a legal contract. If you are describing a peaceful, quiet contentment, 开心 might feel too loud. It implies a bit of a smile or a laugh. If you are just "okay," this is too strong.

The idea of an "open heart" is deeply rooted in Chinese medicine and philosophy. A closed heart is seen as blocked or stagnant. An open heart allows energy to flow freely. In modern culture, being 开心 is the ultimate social goal. It is what parents wish for their children above all else. It is a very selfless kind of joy often shared with others.

You will often hear 不开心 (bù kāixīn) for being upset or moody. It is a soft way to say you are sad without sounding dramatic. Another one is 开开心心 (kāi kāi xīn xīn). Doubling the characters makes it sound cuter and more emphasized. It is like saying "super-duper happy." You will see this on New Year cards or hear it when talking to kids.