The Japanese language does not include letters as the Western written systems do. Derived from Chinese, Japanese is a primarily ideographic script, with two syllabic alphabets to supplement it. The two Japanese syllabic alphabets are hiragana and katakana. Each has a different context for use and includes the same syllables.
The syllables in the Japanese language consist of simple consonant-vowel combinations such as "mu," ba" and "nyu." There are 105 syllables used in Japanese syllabic script. Hiragana is a more curved, flowing script, used for native Japanese words and often in combination with kanji. When hiragana is combined with kanji, it is known as furigana and is used to demonstrate the proper reading of a kanji. Hiragana are often used in children's books because children may not have a solid grasp of kanji.
Katakana uses the same syllables as hiragana does. However, it has a sharper, more angular appearance and is used for foreign words by writing the syllables that most closely approximate the sound of the word. For example, "Spain" in katakana would be written using the syllables "su," "pe," "i" and "nu." When learning Japanese, it's best to start with hiragana, then work through katakana and up to kanji.