Quick meaning
An app that generates time-limited codes used as a second factor for logging in, instead of receiving an SMS.
Think of it like this
Like a physical security token that shows a changing number only you can see.
Where you may see this
You may see this in login screens, warning messages, banking apps, or scam-prevention advice.
Why it matters
Understanding this word helps you protect your money, personal information, and online accounts.
Say it simply
Authenticator App means: An app that generates time-limited codes used as a second factor for logging in, instead of receiving an SMS.