Kanji, Katakana and Hiragana are combined to form phrases in japanese, you use each one depending of the kind of word. The main characteristics are: Kanji: * Ideographic writen system * In total about 50.000 characteres, but 2,136 are officially aproved to use in Japan * Most of the characteres have readings originated from China and originated from Japan Hiragana: * Has just 46 basic characteres * Is a phonetic sillabic system * The origin is from kanji, especifically from brush styles in calligraphy * Is used to write words mainly of japanese origin, specially conjugations or words that don't have kanji or you don't know the kanji Katakana: * Has just 46 basic characteres * Is a phonetic sillabic system * The origin is from Kanji, especifically parts of some kanjis * Is used to write mainly foreing words, but has another uses like onomatopoeias, names of very popular japanese people, or just to remark a word that usually is written in kanji or hiragana

http://www.saiga-jp.com/japanese_language.html Hope it helps :))

Katakana = western words, mostly from English Kanji = meaningful parts of speech, like nouns, adj., verbs, adverbs etc Hirigana = grammar indicators