1. Kanji (漢字): Logographic characters borrowed from Chinese, each representing a word or morpheme. There are thousands of kanji, and learning them is a significant part of mastering Japanese writing.
2. Hiragana (ひらがな): A phonetic syllabary, with each character representing a syllable. Hiragana is used for grammatical particles, verb endings, and words that don't have a kanji representation.
3. Katakana (カタカナ): Another phonetic syllabary, but used for foreign words, onomatopoeia, emphasis, and proper nouns.
While these three systems are the most important, there is a fourth system called Romaji (ローマ字).
Romaji is a system of writing Japanese using the Latin alphabet. It is mainly used for transliteration and for teaching Japanese to beginners. While not a true "writing style" in the same way as the other three, it is used frequently, especially in the digital age.
So, in summary:
* Three main writing systems: Kanji, Hiragana, Katakana
* Fourth system: Romaji, used for transliteration and teaching