Kanji are a set of characters used in Japan. These characters are pictographic representations of words or ideas. The standard set of kanji is about 2000 characters ranging from 1 stroke to 23 strokes; however, many characters not contained in this list are commonly used in Japan, so the real number is at least 4000.
Often kanji are referred to as Chinese characters; however, this is misleading. Most kanji were imported from China, but several were developed in Japan and hence can’t be read by the average Chinese person. Also, over the centuries, characters have been modified in China and in Japan independently, so there has been a divergence.
Most kanji have at least one on (音) reading and at least one kun (訓) reading. On means ‘sound’ and refers to readings derived from Chinese readings for the same character. Derived being an operative term here since Chinese language contains sounds and tones not used in Japanese. As a direct result, many characters have identical on readings. Kun means ‘explanation’ or ‘read’ and refers to Japanese words assigned to the characters. Usually these meanings are similar to the Chinese meanings, but occasionally they differ greatly.
Often kanji are used in two or three character combinations. These jukugo are similar to compound words in English (or more appropriately; German, since English usually uses two words in compounds). Sometimes jukugo of four or five characters are used, but the writer has found these to really be sets of two or three on most occasions. (i.e., 自動販売機 is ‘vending machine’, a combination of ‘automatic’, ‘selling’, and ‘machine’.)
Occasionally, old versions of characters are still used as well; particularly in place names. Also, old words have been attached to kanji without regard to readings. These exceptions typically have to be memorized. One example is Yamato (大和), the original name of Japan from more than 2600 years ago. One is tempted to read it as ‘daiwa’ without any other direction.