Romaji: The Evil 4th Type of Japanese Character
In the image below, we have hiragana, katakana, and kanji, which are actual Japanese characters. Sometimes, though, you will see Japanese words written using the Latin alphabet. These characters are called rōmaji (ローマ字)… but everyone is too lazy to write “ō,” so usually it will be written as romaji:
If that sentence above were written in romaji, it would look like this:
Tomu wa piza ga daisuki desu.
For absolute beginner students of Japanese, it can be tempting to use romaji as a crutch. Doing this makes you a horrible person. No, I'm just kidding. But you might feel like a horrible person because your hardcore classmates will make fun of you, and your Japanese teacher will pity you for being a stupid foreigner that can’t learn “complicated” scripts like hiragana and katakana (← false, offensive misconception).
There are only about 50 characters for both hiragana and katakana, so I recommend memorizing them as early in your studies as possible. That is, after all, one purpose of this free course. ^_^
Note: If your only goal for Japanese is to reach a conversational level, never reading books, signs, subtitles―whatever―then it's not the end of the world if you use romaji. If you try to put a language like, say, Thai into roman letters, you start to run into a whole slew of pronunciation problems. Japanese, however, can be represented by roman characters with a fair amount of accuracy. That said, anyone taking their studies seriously will learn, at a minimum, hiragana and katakana, because it enables you to interact with so much more Japanese content (like, for example, my daily lessons, which don't use romaji).