particles

Non-conjugate words that attach to main words and indicate the relationship of those words to the following word or the remainder of the sentence. There are also sentence-final particles that may comment grammatically on the entire sentence. Some Japanese particles function in a manner similar to English words. For example, in the phrase sensei to gakusei (teacher and student) the particle to functions as the conjunction "and." Other particles have functions similar to prepositions but they are placed after the words they modify, e.g., Tokyo e (to Tokyo), Oda-san to (with Mr. Oda). Still other particles have no equivalents in English, such as wa or o, which are attached to the topic (subject) or object of a sentence respectively, as in Honda-san wa isha desu (As for Mr. Honda, he's a doctor) and Hon o yomimashita (I read a book). Are particles important? Absolutely. They must be learned in order to speak proper Japanese. (excerpt from The Japanese Particle Workbook, by Kamiya Taeko. 1998, Weatherhill Books).