To notify someone means to formally tell them about something important, usually something they need to know or have a right to know. When your school notifies parents about an upcoming field trip, they're making sure families have the information they need to prepare. When a library notifies you that your book is overdue, they're officially informing you so you can return it.

Notification is more official than just mentioning something. You might casually tell your friend about weekend plans, but a company notifies customers when their order has shipped. The post office notifies you when a package arrives. A weather service notifies communities about approaching storms.

The word suggests responsibility and timeliness: when someone needs to notify you, they have a duty to make sure you actually receive and understand the information. That's why important notifications often come in writing, through email, letters, or official announcements. If your teacher needs to notify students about a test date change, she might announce it in class and write it on the board to make certain everyone knows.