In Chinese thought, one of the two forces that make up everything — the active, bright, warm, outward, moving one. Its partner is yin: still, dark, cool, inward, receiving. The pair are not good and bad, and they are not enemies. The whole idea is that neither exists alone: each contains a seed of the other, each turns into the other, and health, weather, mood and the world work well only when the two are in balance.

In Chinese thought在中文的思想裡, one of the two forces that make up everything構成萬物的兩股力量之一 — the active, bright, warm, outward, moving one就是主動、明亮、溫熱、向外、會動的那一股。 Its partner它的另一半 is yin是 yin（陰）: still, dark, cool, inward, receiving靜、暗、涼、向內、承接的那一股。 The pair這一對 are not good and bad不是好與壞, and they也不是 are not enemies彼此的敵人。 The whole idea整個概念 is that neither exists alone是兩者都不能單獨存在: each contains a seed of the other彼此心裡都藏著對方的種子, each turns into the other彼此也會轉變成對方, and health, weather, mood and the world work well only when the two are in balance而健康、天氣、心情和世界，只有在兩者平衡時才會運作良好。

English borrowed the word along with the idea, and in English it appears almost always beside yin, most often in the fixed phrase "yin and yang" — notice that English says yin first, though Chinese usually says 陰陽 with 陰 first too.

EnglishEnglish borrowed the word along with the idea把這個字連同這個概念一起借了過去, and in English而在英文裡 it appears almost always beside yin這個字幾乎總是跟 yin 一起出現, most often in the fixed phrase "yin and yang"最常見於固定說法「yin and yang」 — notice that English says yin first要注意英文是把 yin 放在前面, though Chinese usually says 陰陽 with 陰 first too雖然中文的「陰陽」通常也是「陰」在前。

Beyond the philosophy, English speakers use "yin and yang" loosely for any pair of opposites that need each other: two colleagues, two halves of a personality, work and rest. That loose use is very common and quite far from the original.

Beyond the philosophy除了哲學上的意思, English speakers英文使用者 use "yin and yang" loosely也會鬆散地用「yin and yang」 for any pair of opposites that need each other指任何互相需要的一對相反事物: two colleagues像兩個同事, two halves of a personality一個人性格的兩面, work and rest工作和休息。 That loose use這種鬆散的用法 is very common and quite far from the original很常見，但離原意已經很遠。

In Chinese medicine, though, the word keeps its full weight: too much yang, not enough yang, and so on. Small notes: it is a common noun with a small y, no "the" in the phrase ("yin and yang", not "the yin and the yang"), and it can sit in front of another noun — yang energy, yang foods.

In Chinese medicine在中醫裡, though不過, the word keeps its full weight這個字還是保留完整的份量: too much yang, not enough yang陽太多、陽不足, and so on等等。 Small notes幾個小提醒: it它 is a common noun with a small y是普通名詞，字首小寫, no "the" in the phrase這個片語裡不加「the」 ("yin and yang", not "the yin and the yang"是「yin and yang」，不是「the yin and the yang」), and it而且它 can sit in front of another noun可以放在另一個名詞前面 — yang energy, yang foods像 yang energy、yang foods。