An automated external defibrillator, or AED for short, is a special device that can help save someone's life when their heart is having a big problem.
You see, our hearts have a special job - they pump blood all around our bodies to give us energy and keep us healthy. But sometimes, for different reasons, our hearts can get confused and they start beating in the wrong way or even stop working altogether.
Now, doctors and nurses can give special medicines or do special operations to try and fix the heart, but sometimes that's not enough. This is where the AED comes in - it's kind of like a superhero for the heart!
If someone's heart is in trouble, someone else can grab the AED and put it on the person's chest. The AED will start talking and telling the person what to do. The AED will also automatically check the person's heart to see if there's a problem that it can help with.
If the AED finds something wrong, it will give a big shock to the person's chest. This may sound scary, but it's actually a good thing, because the shock can help restart the heart and make it start working properly again.
That's why it's so important to have AEDs in public places and for people to know how to use them. They can help save someone's life and make sure their heart keeps doing its special job.