A memo is a short written message used inside an organization to share information, give instructions, or make announcements.

In an office, a manager might send a memo to remind everyone about an upcoming meeting or to explain a new policy. In a school, the principal might distribute a memo to teachers about changes to the schedule. Memos are meant to be clear and direct, getting straight to the point without unnecessary details.

Unlike a letter, which often goes to people outside an organization and includes formal greetings, a memo typically stays within a company or school and uses a simpler format. It usually starts with “To,” “From,” “Date,” and “Subject” at the top, making it easy to see at a glance what it's about and who sent it.

People sometimes say they “didn't get the memo” when they miss important information everyone else seems to know about. If your friends all show up wearing costumes to school on Spirit Day and you're in regular clothes, you might joke that you didn't get the memo.