There are 3 Japanese scripts : Hiragana, Katakana & Kanji. Mostof the Japanese sentences are written in Hiragana, Katakana & Kanji, all three.
Hiragana is used for the endings of verbs and for grammatical particles.
Katakana is used for transcription of words borrowed from foreign languages (except Chinese), like country names, personal names, etc.
Both Hiragana and Katakana letters are a phonetic representation of sound, representing exactly the same set of sounds.
Kanji, which is a set of Chinese characters called sinograms, is used for the nouns and the radicals of verbs.
The Hiragana script has a Kanji equivalent (excepts the endings of verbs and the particles).
The Katakana script does not have a Kanji equivalent.
Whereas Hiragana and Katakana are phonetic representations of sound, Kanji conveys sounds as well as meanings.
A sentence in Japanese can be written in Hiragana and Katakana only (without Kanji).
Romaji (Roman letters) is simply the transliteration of Japanese in the Latin script. It is sometimes used for the convenience of foreigners, mostly on sign-boards and at stations.
The Romaji vowelsā,ī, ū,ē signify emphasis, and hence are also written asaa, ii, uuetee. ex.īe = iie
The vowel ō becomes ou and notooex. gakkō = gakkou
In Katakana, the emphasis on the vowel signifies a long sound written as ー. ex.nōto (notebook), will be written in katakana as : ノート
Example. The sentence 'Little Theresa is six years old' is written in :
Japanese Romaji : Teresa chan wa roku sai desu ;
Japanese traditional (Hiragana, Katakana and Kanji) : テレサちゃんは六歳です。; where Kanji = 六 (roku = six),歳 (sai = years old) ; Katakana = テレサ(Teresa = Theresa) and the rest is Hiragana.
Japanese Hiragana and Katakana (without Kanji) : テレサちゃんはろくさいです。 Note - The Kanjis in the sentence written in Japanese traditional, 六 and 歳 are replaced by their hiragana equivalents ろく(roku) andさい(sai) respectively.
Exceptions : 'I am 20 years old' is said in Japanese as : Watashi wa hatachi desu. (not Watashi wa nijūsai desu)
The pattern after 20 is : 21 = nijuuichi; 22 = nijuuni and so on. The same pattern follows upto hundred. Hundred 100 = hyaku. 200 = ni hyaku. However there are 3 exceptions to this : 300 = sanbyaku ; 600 = roppyaku and 800 = happyaku. The rest follow hyaku. Likewise thousand = sen. 2000 = ni sen, but 3000 = sanzen and 8000 = hassen. The rest follow sen.
Note : 'Chan' is used as a suffix to a child's name and is the equivalent of Miss and Master.
は(ha) is read (wa) only when it is used as the particle attached to the noun or the subject of a sentence. In other words, one writes は notわ for the particle wa. は(wa) is always used after the subject. In the example above, は(wa) comes after the subject Teresa テレサ.
Reverse Quiz
Notes 
