Hanyu Pinyin is the romanization system used in the People's Republic of China for Standard Mandarin. It is also the system most international learners meet first. Each Chinese syllable is written with Latin letters. Tones are written with marks over vowels or, in some tools, with numbers.
Pinyin is for pronunciation and input. It is not a replacement for characters in formal writing, and it is not English. qing is not the English word qing. shi is not a hint that the syllable sounds like English she. The letters are a convention that Chinese schools and ISO standards agreed to use.
Taiwan officially teaches Zhuyin (bopomofo) in primary school and also uses romanization in some public signage and language materials. Hong Kong daily speech is often Cantonese, which has its own romanization traditions. When this site says Pinyin, it means Mandarin Hanyu Pinyin unless a sentence says otherwise.
Initials, finals, tones
A Mandarin syllable is usually described as an initial plus a final, then a tone. In zhong, the initial is zh and the final is ong. The first tone is written zhōng. The same letters with another tone are a different syllable to a Mandarin speaker.
Not every syllable has a written initial. an, en and ou begin with a vowel in Pinyin (sometimes with a hidden glide in speech). y and w are spelling devices that keep syllables readable when they would otherwise start with i or u.
Tone is not decoration. mā, má, mǎ and mà are different dictionary items. The four tones page walks through the contours and the neutral tone. If you leave the marks off, you are writing a skeleton, not standard Pinyin.
What Pinyin is for
Teaching. Beginners need a way to read pronunciation before they know two thousand characters. Teachers write Pinyin above a line, beside a line, or instead of a line for the first weeks.
Input. Most people who type Simplified Chinese on a phone do it with Pinyin. You type nihao, pick 你好, and the characters enter the document. The Pinyin itself is not stored unless you keep it on purpose.
Reference. Dictionaries list readings in Pinyin. Linguists argue in Pinyin. A converter that writes Pinyin next to characters is building a reference layer, not a new essay.
Pinyin is a poor substitute for characters in names on legal forms, in published books for native readers, and in any context where homophones would collide. Chinese has many syllables that share a spelling once you ignore tone, and still many that share a spelling even with tone.
What Pinyin is not
It is not Traditional or Simplified conversion. 中国 and 中國 can both be written zhōngguó. If you need the other character set, use the text converter first or instead.
It is not translation. wǒ xuéxí zhōngwén does not explain the sentence to someone who does not know the words. See conversion vs translation if that mix-up is why you opened this site.
It is not a single reading for every character. Polyphones (多音字) exist. 行 may be xíng or háng. 了 may be le or liǎo. A library guesses from context.
What this site can do
The Pinyin converter reads Chinese characters and writes Pinyin, from pasted text or from a file. The Pinyin Writer is for people who already type letters and tone numbers such as ni3 hao3.
Continue with the four tones, tone marks vs tone numbers, or how to add Pinyin to Chinese text.
Frequently asked questions
Is Pinyin only for foreigners? No. Chinese schools use it to teach pronunciation and to look up characters. Adults still use it to type.
Should I write spaces between syllables? Teaching materials often space by word or by syllable. Native running text does not include Pinyin at all. Pick a house style and stay with it.
Why does ü look like u or v in some tools? ü is awkward on keyboards. Many IMEs accept v for ü. Printed Pinyin should still show ü or the u-with-umlaut on ju, qu, xu, yu as the spelling rules require.
Is Wade-Giles the same thing? No. Wade-Giles is an older romanization. You still see it in some names (Tao, Peking as historical forms). Hanyu Pinyin is the current default for Mandarin teaching materials from the PRC.
Can Pinyin write Cantonese? Not as a complete system. Cantonese needs its own romanization and a different tone set.