Okay kiddo, sometimes people try to hurt other people by using germs, viruses, or toxins. That's where biodefence comes in! Biodefence is all about keeping people safe from those bad things.
There are a lot of different ways to do biodefence. One way is to make sure that we have the tools we need to detect when there might be dangerous germs or viruses around. Scientists can use special tests to check for those bad things in the air or on surfaces.
Another way to do biodefence is to make sure we have medicines that can help people if they get sick from those bad things. Sometimes people can get very sick or even die from things like anthrax or smallpox, but doctors and scientists have worked hard to make medicines that can help.
We can also try to prevent people from getting sick in the first place. That means washing our hands with soap and water, covering our mouth and nose when we sneeze or cough, and staying home if we're feeling sick.
There are people called "biodefense experts" who spend their whole careers working on ways to keep us all safe from those bad germs and viruses. They do things like investigating outbreaks to figure out what happened and how to prevent it from happening again.
So, biodefence is all about protecting people from bad germs and viruses. It involves detecting those things, treating people who get sick, and preventing people from getting sick in the first place. It's really important work, and there are experts who dedicate their lives to it!