- Kanji (literally "Han characters") are logographic characters borrowed from Chinese, together with a few characters that were coined or simplified in Japan, to represent words according to their meanings. The jōyō kanji are the 2,136 characters (as of 2010) that are taught in Japanese schools and are most commonly used in words, and 983 more kanji are approved for use in personal names, but thousands more are known to exist. Kanji often have several different pronunciations in Japanese depending on context, and variant pronunciations are often exploited for wordplay (see e.g. Goroawase Number). The various phonetic readings of kanji, which must be memorized individually, are classed either as on'yomi ("sound" reading) or as kun'yomi ("meaning" reading); a given character could have more than one reading of each kind, or only one of either. Kanji may also have nanori readings used only in personal names, though people are hardly expected to memorize most of these.
The on'yomi derive from the morphosyllabic character readings of the Chinese Language, but due to Japanese having a simpler phonetic system than Chinese, they often include vowel modifications or consonantal suffixes (usually tsu, ku, ki, chi or n). This contrasts with the predominantly multisyllabic kun'yomi, which mainly represent yamato kotoba, the indigenous Japanese language. ("Zero" is one of the very few loanwords to be adopted as the kun'yomi of a character.)
The most common on'yomi are the kan-on readings, adapted from Chinese as it was pronounced during the Tang dynasty, followed by the older go-on readings, which date as far back as the 5th century; these readings tend to correspond vaguely at best to modern Chinese pronunciations of the same characters, but for the same reason they have been very useful for linguists trying to reconstruct Middle Chinese.
- Ateji (literally "assigned characters") are compounds of kanji in which the sounds of the readings are used without regard to the characters' meanings; this is used for some native Japanese words (e.g. "sushi" and "kabuki") as well as some loanwords and foreign names. Ateji is also used to refer to the opposite process, jukujikun, where a multi-character compound is given a reading not based on kun'yomi or on'yomi but corresponding to meaning only.
- Kana refers to syllabaries capable of writing all sixty-odd phonetic sounds in the Japanese language. (Technically kana represent not syllables but morae. The difference probably won't matter to you.). Each of the two syllabaries used today has 46 (formerly 48) basic characters representing the five vowels (A, I, U, E, O) either singularly or in combination with the consonants K, S, T, N, H, M, Y, R, W note , plus the vowelless n. Some of these base characters can be modified by diacritics: a pair of short strokes (dakuten) changes the initial consonants K, S, T, H into the voiced consonants G, Z, D, B, and a small circle (handakuten) changes H into P. In modern Japanese, the small tsu (sokuon) represents a glottal stop, doubling the following syllable's consonant, and small versions of ya, yu and yo change the i vowel sound of the previous syllable into a glide. (The symbol resembling a small katakana ke, however, is actually shorthand for a counter word pronounced either ka or ga.)
- Man'yōgana were the earliest, nonstandardized attempts at using Chinese characters to represent Japanese sounds. Named for the Man'yōshū, the oldest surviving anthology of Japanese poetry dating from the Nara period, though earlier examples of man'yōgana have been found. The Iroha-uta, a famous poem whose 47 characters formerly defined the phonetic ordering system for Japanese, was originally written in man'yōgana.
- Hiragana originated as a simplified version of Chinese cursive script, which in ancient Japan was practiced mainly by women; The Tale of Genji was written primarily in hiragana. Many variant hiragana characters existed until 1900, when a unique set was codified. In modern Japanese, hiragana is the "everyday" system for writing the particles that are essential to sentence structure, and the okurigana suffixes used to inflect verbs and adjectives. Many everyday idiomatic expressions are more commonly written in hiragana rather than kanji. Vowel sounds are lengthened in hiragana by tacking on additional vowel characters, though straight or curved dashes may be used instead in informal writing, particularly when hiragana is used in place of katakana for the sake of cuteness.
- Katakana is more angular than hiragana. It was probably invented sometime during the Heian period by Buddhist monks, who used it to insert Japanese particles into Chinese texts, and is still used in dictionaries for writing on'yomi. Nowadays, however, katakana is the usual way of writing loanwords and foreign names in Japanese text, though this tends to distort their pronunciations in ways that Japanese Romanization often attempts to correct for. Besides its use to represent foreign words, katakana is also used for onomatopoeia, for emphasizing words, and for some personal names. In katakana, long vowels are represented by a dash following a character. To reduce pronunciation distortions, "extended kakatana" adds several additional symbols that are sometimes used for representing sounds that are not part of the Japanese language, particularly "v" (「ヴ」).
- Furigana, also known as "ruby" characters, are small hiragana or katakana written above kanji or rōmaji to show how they are intended to be pronounced. Furigana tends to be ubiquitous in works written for younger readers, who are not expected to know very many kanji. Furigana is a conventional way of indicating how the kanji in people's names should be read, particularly on business cards and so that Chinese people can have their names pronounced closer to modern Chinese than the on'yomi reading. They can also be used for creative Alternate Character Readings.
- Rōmaji are Roman letters used for the exact representation foreign names. They can also be used as initials, in which case they are pronounced approximately as they would be in English. "L" and "R" are distinguished (pronounced "eru" and "aru", respectively), as are "V" and "B" ("bui" and "bii"). Romanized Japanese text is also known as rōmaji.
- Yakumono (punctuation) was not originally part of Japanese writing, but was adopted on the Western model during the Meiji Restoration. Punctuation marks in printed Japanese look different from their Western counterparts, not least in that they are almost invariably monospaced (like other Japanese characters).
- Spaces are not inserted between Japanese words. In the rare cases where words require separation (especially transliterations of foreign phrases), the interpunct (・) is used.
- Periods (。) and commas (、) are modified to look more Japanese, but are used more or less as in Western writing, though with slightly less consistency.
- Single quotation marks (「 」) and double quotation marks (『 』) are shaped very different from their Western counterparts, and are used to set off titles and even proper nouns as well as quotations.
Useful Notes / Japanese Writing System
The Japanese Language left no written record before the seventh century CE, when Japan was absorbing a lot of Chinese culture, including their way of writing and a large amount of vocabulary. While retaining its distinctive phonetics and grammar, Japanese began to acquire loanwords from Western languages in the sixteenth century onward, a process which intensified during the Meiji period. Due to this linguistic history, modern Japanese has a uniquely complex writing system, which combines logography with syllabaries.