Hiragana: The hiragana script (written ひらがな in hiragana) is a cursive script still mostly used for:
* Particles, e.g., が ga, の no, and は ha (pronounced wa).
* The endings on verbs, e.g., る ru, た ta, ます masu, etc.
* Grammatical words such as この kono ‘this’.
* Words where there are no suitable Chinese characters or the Chinese characters are too difficult for ordinary use, e.g. 林檎 ringo ‘apple’ is normally written in hiragana as りんご.
Children first learn to read and write in hiragana.
Katakana: The katakana script (written カタカナ in katakana) is a blocky-looking syllabary now mainly used for
* Foreign words, e.g., デパート depaato ‘department store’, クレジットカード kurejitto kaado ‘credit card’, コンテナー kontenaa (freight) container’, etc.
* Scientific names of plants and animals, e.g., ゾウ zou ‘elephant’, トビ tobi ‘kite’, even ヒトhito ‘person’.
* Onomatopoeic words, e.g., ガタガタ gata gata ‘rattling/rickety sound’.
Ja, mata ne.
Note: The site also contains the topic “Could Kanji be replaced with Kana?”. You can read there several good reasons hy hiragana have failed to replace Kanji.