User blog comment:Mikuru Kanzaki/Learn Japanese from other users!/@comment-5707992-20160531231014/@comment-5707992-20160602213302

Kanji, along with hiragana and katakana, are used in the modern Japanese writing system - it's never just one which is why you see all three used in sentences. What makes it so complicated is how to use the kanji and kana and to know how to use them, it's recommended you learn what exactly is each character system:

Kanji - this is the system that is based off of Chinese hanzi (all three are based off some Chinese hanzi, but the kana, due to be so simplified, no longer carry the meaning of the character they may have originated from). They're what's known as "logographic" meaning a written character represents a word or a phase.

Hiragana - this is actually my favorite writing system for two reasons: appearance and function. Hiragana is used for Japanese words that either don't have a Kanji character, or used in place of any obsure traditional Kanji characters. Particles are a big example of this. They're also used for the pronunciation of certain characters (the little symbols you see at the top of the character).

Katakana - this one gave me so much trouble when I was learning. Katakana is the system that places characters for foreign words. So whenever you hear a foreign word of any kind being used (and it sounds like it would in the original language, mind the Japanese accent), that's katakana.

Context and also sentence structure are importants part of knowing which to use though. Because there are a lot of characters with the same or similar meaning, learning sentence structure and context will help you get a better understanding of how they writing it.

Hope this explanation wasn't too confusing.