Hiragana and katakana developed almost simultaneously, but independently and for different reasons. This took place a little over a thousand years ago. In modern usage, katakana are used to represent words whose origins are foreign languages other than Chinese.
Unlike hiragana, katakana symbols are not so cursive. They have sharp angles and more straight lines. We will introduce katakana in the same way as we did for hiragana. Basically, the rules for katakana are the same as those for hiragana, except for double (or long) vowels. Examine the following:
おかあさん okaasan (mother)
スプーン supuun (spoon)
おおきい ookii (big)
スケート sukeeto (skate)
As you see in the above example, double (or long) vowels are written with a straight line in the case of katakana, instead of writing the symbol for that vowel. Here are some more examples:
ケーキ keeki (cake)
スキー sukii (ski)
コーヒー koohii (coffee)
レコード rekoodo (record)
Other rules (such as those for double consonants, consonant + y + vowel) are exactly the same as for hiragana. Note that, since you have already learned to construct the voiced sounds, and the double/long vowel has been introduced above, we will use those in examples and practice exercises from the beginning.
In addition, katakana has a few more combinations of symbols than hiragana does. Some additional symbols are listed below; these are a device used to suggest the closest pronunciation of the foreign word in question.