are the basic characters, and katakana are another
basic characters for Japanese language.
They were created for writing kanji speedily since the 9th century. For the purpose, most katakana characters are the part of a kanji.
Katakana are mainly used for writing names of foreign people and
places, foreign words and imitation sounds.
Recently we tend to use any English words without change, so we find very much katakana words everywhere.
So the newspaper and broadcast make an effort to use Japanese words as much as possible.
One or two characters of katakana describe a Japanese syllabic sound like the following like hiragana.
Unlike alphabet, katakana does not distinguish a character of
big letter from small letter.
There are the small letters of "tsu", "ya", "yu" and "yo", but they have special meanings.
Now the sounds "si", "ti", "tu", "zi", "di" and "du" have changed to "shi", "chi", "tsu", "ji", "ji" and "zu".
"Wo" is only used as a postposition.
For the sounds "f", "v" and so on which don't exist in Japanese
language, there are some writings.
But the sound "l" is only written by the characher of "r" sound.