Like hiragana, katakana is an alphabet used to represent the sounds of Japanese words. But why are two alphabets necessary for this?!? The simple answer is that while hiragana is used to write most Japanese, katakana is used when writing foreign loan words, often words taken directly from English.
Click on any of the characters in the table below to see how to write it correctly:
Just as with hiragana, by adding two small vertical dashes or a small circle, the pronunciation of the katakana for "ha" becomes "ba" or "pa". The chart below contains the complete list of possible combinations:
Similarly, when a ya, yu, or yo sound follows certain characters, the sound is shortened and so instead of two separate characters, the sound is written as the combination of the first character and a small, subscripted version of the ya, yu, or yo sound that follows: