に (NI) is used to locate a place (今会議室にいます, Ima kaigijitsu ni imasu, I'm in the meeting room now).
に is frequently used after spatial locators "on, at, in, next to, etc."
卵は冷蔵庫の中にあります。
Tamago wa reizouko no naka ni arimasu.
The eggs are in the refrigerator.
2.
The particle に (NI) can be used to mark time, and can be used in many situations (hour, date, length, season, etc.).
午後3時半に駅で会いましょう。
Gogo sanji han ni eki de aimashou.
Let’s meet at 3:30 PM at the station.
4月8日に結婚しました。
Shigatsu youka ni kekkon shimashita.
I got married on April 8th.
3.
Expresses a movement toward a precise destination. へ (pronounced "E" and not "HE" in that case) is also used, but focuses more on the direction than on the destination.
学校に行きたくない。
Gakkou ni ikitakunai.
I don’t want to go to school.
4.
に (NI) can be used after the conjunctive base of a verb to express the goal of an action. The conjunctive base is the one used with polite form -MASU (SHImasu, TABEmasu, etc.). This structure can be translated as "in order to do."
木村さんは本を借りに図書館へ行きました。
Kimura san wa hon o kari ni toshokan e ikimashita.
Mr. Kimura went to the library to borrow a book.
5.
Designates an action's recipient in structures such as "to give to someone," "to send to someone," "to ask someone," "to teach someone," etc.
弟は犬にえさをやりました。
Otouto wa inu ni esa o yarimashita.
My younger brother gave food to the dog.
6.
In the structure "noun + に (NI) + verb of movement," the particle に can denote an inward movement. For example, to enter a room, but also in a more abstract way (to participate, to enroll, to meet, etc.).
知らない人が私の家に入って来ました!
Shiranai hito ga watashi no ie ni haitte kimashita!
A stranger has entered my house!
山田さんはそのプロジェクトに参加しました。
Yamada san wa sono purojekuto ni sanka shimashita.
Mr. Yamada took part in this project.
7.
に (NI) is used to indicate the result of a change, mainly with the verb "to become." There is an idea of movement from one state to a new state.
キャンディーを食べて舌が緑色になった。
Kyandii o tabete shita ga midoriiro ni natta.
I ate a candy and my tongue became green.
8.
In a passive structure, に (NI) is used to indicate the agent, the grammatical element that is at the origin of the action (by him, by the train, etc.)
先週の日曜日彼女に振られた。
Senshuu no nichiyoubi kanojo ni furareta.
I was dumped by my girlfriend last Sunday.
9.
In a causative sentence (to make someone do something), に (NI) is used to indicate the person who is made to do something.
上司は私に残業させました。
Joushi wa watashi ni zangyou sasemashita.
My superior had me do extra hours.
Be careful, in a passive-causative structure (to be made to do something by someone) it can become complex to identify the right elements correctly, に is used to indicate the agent (the one is at the origin of the action).
父に芝生を刈らされました。
Chichi ni shibafu o karasaremashita.
I was made to mow the lawn by my father.
10.
に (NI) introduces the information on which an action is based. It can often be translated as "according to, based on, etc."
税金は収入に基づいて決められる。
Zeikin wa shuunyuu ni motozuite kimerareru.
Taxes are calculated based on the revenue.
11.
に (NI) can be used to make an enumeration of elements usually in a written style. When speaking, it's more common to use the particle と (TO) or や (YA) instead.
松田さんは犬に猫にウサギを飼っています。
Matsuda san wa inu ni neko ni usagi o katte imasu.
Mr. Matsuda has a dog, a cat and a rabbit.
12.
に (NI) is used to indicate the basis for a comparison, the criterion on which the comparison is built.
ジョンさんはお母さんに似ている。
Jon san wa okaasan ni nite iru.
John looks like his mother.
4人に1人の人がアレルギーで苦しんでいます。
Yonin ni hitori no hito ga arerugii de kurushinde imasu.
One person out of four is suffering from allergies.
13.
に (NI) is used to emphasize the meaning of a verb when using the following structure: "Verb (conjunctive base) + に + Verb."