Quick meaning
A notification or message that appears inside an app while you are using it.
Think of it like this
Like a waiter tapping your shoulder while you're seated to let you know about a special.
Where you may see this
You may hear this in email apps, messaging apps, video calls, and workplace instructions.
Why it matters
Knowing the term makes it easier to message people correctly and avoid simple communication mistakes.
Say it simply
In-App Message means: A notification or message that appears inside an app while you are using it.