Japanese has two phonetic scripts that cover the exact same set of sounds. They are not interchangeable. The script a word appears in carries meaning of its own.
Hiragana: the default
Hiragana handles native Japanese words, grammar, particles, and verb and adjective endings. It is the rounded, flowing script. Most of a normal sentence that is not kanji is hiragana.
taberu, to eat, written in hiragana
watashi wa, I (topic), the は is a hiragana particle
Katakana: the foreign and the loud
Katakana, the sharper, angular script, marks words that stand apart from native vocabulary.
Loanwords
Words borrowed from other languages. コーヒー (koohii, coffee), コンピューター (konpyuutaa, computer).
Foreign names
Non-Japanese personal and place names. スミス (Sumisu, Smith).
Onomatopoeia and emphasis
Sound words and words a writer wants to make pop, the way italics work in English.
Why the split matters
Seeing a word in katakana is a signal: this is borrowed, foreign, or emphasised. A Japanese reader registers コーヒー as an imported word the moment they see the script. That nuance vanishes in English, where everything uses one alphabet. Our katakana loanwords guide covers the words that look like English but mean something else.
Test one of these examples in the translator and see how it comes out.
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