Katakana (片仮名, literal meaning: "fragmentary kana") is one of two syllabaries used in Japanese writing along with Hiragana. These syllabaries are used in conjunction with a set of ideograms called Kanji borrowed from Chinese; and Romaji, the Roman alphabet. As with the English alphabet, the katakana are used for transliteration, a method to represent one language in the alphabet of another. The other main use of katakana is onomatopoeia, the use of words to imitate sounds. The form of katakana is characterized by squarish lines and is the simplest of any of the Japanese scripts.

Katakana is most frequently used to represent foreign words and names. For example, Wikipedia can be written in Japanese using Katakana as ウィキペディア "u i ki pe de i a".

An example of the onomatopoeia use is ハー, which means sigh because the sound is similar to the sound when you sigh.

Other uses include emphasis and vegetal and animal species names.

Katakana was developed by students who used a part of man'yogana characters as shorthand when writing down words whose proper Chinese characters were unknown. Thus, カ (ka) comes from the left side of 加 (ka).

While used to represent words borrowed from foreign languages, katakana is often limited in its ability to represent them as they sound in the language in question. This is due to the syllabic nature of the phonemes of Japanese. This is of no concern to the Japanese, who prefer pronouncing foreign concepts in their own way anyway. For example, to pronounce "McDonald's" the name of a popular fast food chain, you would say "ma ku do na ru do". Many English words pronounced in katakana are indecipherable to native English speakers.

Sometimes katakana is also used for emphasis, much like using all uppercase letters in English.

Recently some special characters used by linguists have been added to Unicode for transliteration of the Ainu language.

base kana						...	extended with diacritics
	A	I	U	E	O			a	i	u	e	o
	ア	イ	ウ	エ	オ		V3	ヴァ	ヴィ	ヴ	ヴェ	ヴォ
K	カ	キ	ク	ケ	コ		G	ガ	ギ	グ	ゲ	ゴ
S	サ	シ1	ス	セ	ソ		Z	ザ	ジ2	ズ	ゼ	ゾ
T	タ	チ1	ツ1	テ	ト		D	ダ	ヂ2	ヅ2	デ	ド
N	ナ	ニ	ヌ	ネ	ノ
H	ハ	ヒ	フ1	ヘ	ホ		B	バ	ビ	ブ	ベ	ボ
							P	パ	ピ	プ	ペ	ポ
M	マ	ミ	ム	メ	モ
Y	ヤ	-	ユ	-	ヨ
R	ラ	リ	ル	レ	ロ
W	ワ	ヰ	-	ヱ	ヲ		V3	ヷ	ヸ	-	ヹ	ヺ
N	ン

¹: Zi (ji) -Zu (zu) - Di (ji) -Du (zu)

²: Si (shi) - Ti (chi) - Tu (tsu) - Hu (fu)

³: Pronounced like "b" sounds.

In the image below, both hiragana and katakana are shown (grouped vertically).

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