Kanji
Kanji, contrary to both hiragana and katakana, represent meanings instead of just sounds.
Ex. 私 (watashi/watakushi) — I
日 (hi, ni, nichi) — sun/day*
Kanji were introduced to Japan by the Chinese around the 5th Century C.E. As such, there are two ways to read kanji: the on'yomi, or the original Chinese way of reading and the kun'yomi, or Japanese way of reading. The way you read and pronounce a kanji depends on how it's being used.
(*See how that particular kanji has several pronunciations and readings? That's thanks to the on'yomi and kun'yomi systems.)
The kanji writing system is somewhat pictographic, and as a result, is considered by some to be very difficult. All kanji are written by a series of strokes, some as simple as two while others are as complicated as over 20! It is said that there are over 10,000 kanji in the Japanese language, though only a small fraction of this number is used on an everyday basis nowadays.
(Cultural Fact! — The average Japanese person knows about 2,000 kanji.)
Sentence Syntax and Punctuation
Typically, most Japanese write their sentences from horizontally from left to right, just like those of us in the States or other primarily English-speaking countries. However, in the case of print media—including books, newspapers and magazines—sentences are likely to be written vertically from right to left. (And it can be very confusing if you're not expecting it!)
Sentence structure differs from English in that instead of it going (subject, verb, direct object), most simple sentences will go (subject, direct object, verb).
Example of an English sentence:
I (subject) am going (verb) to school (direct object).
Example of a Japanese sentence:
私は (subject) 学校に (direct object) 行きます (verb) 。
(Watashi wa gakkou ni ikimasu.)
I will go to school.
Also, contrary to English, the Japanese sentence typically uses specific particles to note what role a word is playing in a sentence. (Particles will be covered in a later lesson.)
As far as punctuation, the Japanese style is a little different from the English style. The following is a chart of Japanese punctuation marks, followed by their English equivalent:
Period: 。( . )
Comma: 、( , )
Quotation Marks: 「 」 ( " " )
Question Mark: か* ( ? )
Exclamation Mark: よ* ( ! )
Asterisk: * ( * )
(*In Japanese, the markers か and よ are typically used in place of a question mark or an exclamation mark, respectively. However, most young people are using the English equivalents nowadays.)
There is also the special dot mark ( ・ ) and the dash mark ( — ) used with foreign names and places with two or more parts or to elongate a vowel as previously discussed.
Ex. クリスチオン・ベール (Kurisuchion Beeru) — Christian Bale
ニュー・ヨーク (Nyuu Youku) — New York City
(Note: As you can see, this is pretty much a katakana-only thing.)