Okay kiddo, you know how sometimes you get toys or food or clothes that aren't as good as what you expected? Well, grown-ups have the same problem but with bigger things like cars or phones or even buildings.
So, to make sure they get things that are good enough, they have something called Acceptable Quality Limit or AQL. This is like a rulebook that tells the grown-ups how to check if something is good enough to use.
It's like when you play a game and you set some rules to make sure everyone is playing fair. The grown-ups set some rules to make sure everything they get is just right.
Now, these rules say that only a certain number of things can be not-so-good. Sometimes this number is 1 or 2, or even 100. This depends on how important the thing is.
For example, it's okay if there's one small scratch on a toy car, because you can still play with it. But if there's a scratch on a new car, that's not okay.
So, because grown-ups use AQL to check things, they know if something is good enough or not. Now you know too!