Hiragana is the set of symbols used for writing normal Japanese words. Katakana is a different set of symbols used for writing words of foreign origin. Since each symbol represents a unique sound, there are quite a few more symbols than there are letters in the alphabet. In fact, there are 46 basic hiragana symbols, along with another 25 minor variations to some of these base symbols. Here's a picture showing the hiragana set:
Notice the block of 25 characters on the right are based on other characters in the main group from the left, but with simple additions. So, if you know the base character, it's pretty easy to know what sound the modified form is.
The other interesting thing about this table is it represents all the sounds used in the Japanese language. Every word is made from a combination of these sounds. Notice there are some sounds in the English language that don't exist in Japanese. There are also some sounds in Japanese that aren't very easy for an English speaker to pronounce. For example, try to pronounce tsu. If you've never studied Japanese or Chinese before, it's not likely to be easy to say it correctly.
As I already mentioned, there's also a second set of symbols - called katakana - used to write foreign words. This includes the names of non-Japanese people, the names of countries, certain modern inventions (computer), or other items not originally from Japan. Even the phrase coffee milk is written in katakana. (Surprisingly, while coffee milk tends to mainly be found only in the Rhode Island area here in the United States, it's actually a common item (along with coffee soy milk) in Japanese supermarkets. This was a pleasant surprise to this coffee milk fan.) Here's the katakana set:
So, when someone is first learning to read or write Japanese, there's an initial learning curve just to be able to know how to write the sounds of the language. And not only do you have to learn all these symbols once, you have to learn them twice so you can write them as both native language words and foreign words! It's a bit more to memorize than the 26 letters of the alphabet - even if you count both upper and lower case letters. And I won't even talk about then trying to learn the thousands of kanji characters used in every-day Japanese.
Given this large set of symbols to learn, I was looking for helpful tools to aid in learning them. I came across a pretty handy web site that lets you practice learning groups of characters. It can be found here: www.realkana.com. While the tool is quite simple, I found it very useful. It lets you check off different blocks of characters to learn and then it randomly presents them in flash-card form. I have found it easiest to work with learning blocks of 5 characters at a time. Then once I know those 5 fairly well, I'll go back and practice with the previous few blocks and this latest block. Then, once I'm comfortable distinguishing those characters, I'll do some practice sessions with all the ones I've learned so far mixed together. Working this way, I find I can get pretty comfortable with 15 or 20 new characters in an hour or so. But, after that hour of practicing I find I really need to give my mind a break.