Since Japanese nouns (名詞; めいし) don't inflect they are fairly simple to master. They do, however, take particles to indicate their place in sentences.
Some commonly used particles for nouns are: "は"[1], "が" and "を"[2].
Plurals
The Japanese language lacks plurals in the normal English sense. Plural words are usually either preceded with a number and a counter, or simply made understood through context.
A few nouns can also suffix a pluralizing word, such as "たち" or "ら". When referring to a person, "たち" indicates company. For example, めぐみたち can mean "Megumi and more".
Yet others indicate plurality by repetition (e.g., ひと means person and ひとびと means persons.) Written in kanji, the repetition mark, 々, is used (e.g., 人, 人々).
Noun-phrase particles
Japanese word structure, unlike Western languages which allow declensions depending on gender, tense, and many other aspects, maintains constant word forms, which are inflected by particles.
Note that particles always follow the nouns that they mark.