Why do people usually write words using kanji instead of hiragana?


I've been studying Japanese and I realized some kanji are pronounced exactly
like hiragana like 日 is the read the same as ひ.

For example, the verb "write" is written like 書くinstead of かく, and the
pronunciation of 書 is "sho" not "ka", is it wrong to write everything with
hiragana? why do people write with kanji instead of all hiragana?




If you're talking about why kanjis are in the language, this is the history of
Japan with China, you might want to read some literature about the subject.

If you're asking about the utility of using kanji, there is a couple. It's
separating words and grammar in a broad sense (because words don't consist
exclusively of kanjis). Also, the same word can have different kanjis giving
different variations of nuances. Finally, each symbol holds a certain meaning
so, in some sense, you can understand the text without knowing how to
pronounce it. There is also inconvenients, mostly that you need to learn them
all. This is generally known as
[Logograms](https://en.wikipedia.org/wiki/Logogram), if you want to study this
in more details.

Sadly the different
[readings](https://japanese.stackexchange.com/questions/24310/why-are-there-
multiple-katakana-readings-for-a-single-kanji) for the same kanji are an extra
layer of complexity that we just cannot avoid, it's part of the language and
how it evolved. Writing in hiragana is not "wrong" because you'll be
understood, but it doesn't look serious so it will depend on the context. It
would be suited for a casual things like mangas, chatting, learning, etc. But
even then, you'll rarely see text completely in hiragana. For journals,
documents, business and literature, kanjis are mandatory.




If you're talking about why kanjis are in the language, this is the history of
Japan with China, you might want to read some literature about the subject.

If you're asking about the utility of using kanji, there is a couple. It's
separating words and grammar in a broad sense (because words don't consist
exclusively of kanjis). Also, the same word can have different kanjis giving
different variations of nuances. Finally, each symbol holds a certain meaning
so, in some sense, you can understand the text without knowing how to
pronounce it. There is also inconvenients, mostly that you need to learn them
all. This is generally known as
[Logograms](https://en.wikipedia.org/wiki/Logogram), if you want to study this
in more details.

Sadly the different
[readings](https://japanese.stackexchange.com/questions/24310/why-are-there-
multiple-katakana-readings-for-a-single-kanji) for the same kanji are an extra
layer of complexity that we just cannot avoid, it's part of the language and
how it evolved. Writing in hiragana is not "wrong" because you'll be
understood, but it doesn't look serious so it will depend on the context. It
would be suited for a casual things like mangas, chatting, learning, etc. But
even then, you'll rarely see text completely in hiragana. For journals,
documents, business and literature, kanjis are mandatory.

