Frequency data: Jun Da, Modern Chinese Character Frequency List (Middle Tennessee State University), about 193 million characters of modern text, 9,933 distinct characters. Click any character to hear it (uses your Mac's Chinese voice).
The real curve is steeper than 80/20. The top 2,000 (20% of the 9,933) cover 97% of text, and the top 100 cover 42%. Recognising 90% of the characters on a page still means one unknown character in every ten, so reading feels patchy until somewhere around 2,500 to 3,000.
About 80% of characters are built from two parts: a meaning part (the radical, usually on the left or top, e.g. 氵 water, 忄 heart, 扌 hand) and a sound part (the phonetic, usually on the right). The part that gives the sound is usually the right-hand side, and the left side (like 忄 heart) gives the meaning. So 情 = 忄 (feeling) + 青 (qīng) → qíng.
How far to trust it: studies of the sound part put exact matches (same syllable and tone) at roughly a quarter of compounds, around 40% if you ignore tone, and higher again if you accept a rhyme. The sound part is least reliable in the most common characters, which drifted most over 3,000 years of speech, and most reliable in rarer ones, which is where you need it: guessing an unfamiliar character.
The radical tells you what category the word belongs to. With these, a new character like 泳 (氵 water + 永 yǒng) reads as "something to do with water, pronounced about yǒng": swim, yǒng.
| Radical | Means | Examples |
|---|
危 was never the sound part of 脆. The shape arrived by a copying accident.
The older form is 脃. The 2nd-century dictionary 說文解字 explains it as 肉 (flesh) plus a shortened 絕 (jué, "to snap off"): meat that snaps easily, i.e. crisp. Over centuries of handwriting the right side was redrawn as 危, which it resembled, and that shape became standard. In 脆 the 危 gives neither the sound nor the meaning.
The 月 on the left is also not the moon here. It is the squashed form of 肉 (meat, flesh), which is why body and food words carry it: 脸 face, 脚 foot, 肚 belly, 胖 fat, 脆 crisp.
The genuine 危 family is 诡 guǐ, 跪 guì, 桅 wéi, and even those drifted from wēi. Two other ways a sound part fails, both visible in tab 3: sound change over time (也 yě sits inside 他 tā, 地 dì, 池 chí because Old Chinese said them alike), and the 1950s simplification, which sometimes picked a component for its shape rather than its sound.