Katakana in depth
How a foreign word is adapted
Japanese only allows syllables of consonant plus vowel, plus a final n, so any word from abroad is remade to fit. Where English runs consonants together, Japanese slips in a vowel, almost always u, and o after t and d: «strike» becomes ストライク (sutoraiku) and «bed», ベッド (beddo). Long vowels the original does not write appear with the dash: «computer» is コンピューター. That is why reading katakana out loud is the best clue: it sounds like the original word said with a Japanese accent.
Then comes the meaning, which does not always travel intact. マンション is not a mansion but a flat in an apartment block; スマート is said of someone slim and stylish, not someone clever; and カンニング has nothing cunning about it: it means cheating in an exam. Others are invented in Japan from English parts, like サラリーマン, the office worker, or shortened down to four kana: パソコン, リモコン, エアコン. An English speaker in particular should learn them as Japanese words and not assume they already know them.
The sounds Japanese did not have
To get closer to foreign sounds, katakana combines a sign with a small vowel: ファ, フィ, フェ and フォ for f followed by a, i, e or o; ティ and ディ for «ti» and «di», which do not exist in the normal chart, because チ is read «chi»; ウィ, ウェ and ウォ for w; and ヴ for v, although most Japanese speakers pronounce it as a b. These combinations hardly ever appear in everyday hiragana and are read as a single syllable.
Because these spellings are fairly recent, the same word can be written two ways: バイオリン and ヴァイオリン for «violin», or ウイルス and ウィルス for «virus». It is not a mistake, it is the language making up its mind. For the learner, the practical rule is to read the combination as it sounds and not spell it out: ティー is «tī», not «te-i». What does not change is the dash: パーティー has it twice because it has two long vowels, and removing it would change how the word sounds.
The katakana that does not come from abroad
Although it is associated with loanwords, katakana has more jobs. It is used for onomatopoeia and sounds, which in Japanese are a very rich word class: ワンワン is a dog's bark and ドキドキ, a heart beating fast. It is used for emphasis, like our italics or capitals, on signs, adverts and headlines. And it is used for species names in scientific texts, for many brand names and to write the speech of a robot or a foreigner in manga.
Reading it fluently means accepting one thing: at first it reads more slowly than hiragana, because you see less of it. The way to gain speed is to read what is already written in katakana, starting with restaurant menus, packaging and country names. In Hanasuka it has the same listing, the same quiz and the same tracing as hiragana, and the course's everyday phrases are full of katakana, so you practise by reading things people really say.
