Biowar (also called biological warfare or germ warfare) is when people use very tiny living things (like bacteria or viruses) to hurt or kill other people. It's like using an invisible army to fight against an enemy.
So, imagine you have millions of tiny soldiers that you can't see with your eyes. These soldiers are called germs, and they can make you sick. Normally, when you get sick, it's because your body is fighting these germs. But in biowar, people use the germs to hurt others on purpose.
For example, some countries might secretly make germs that make people really sick or even die. Then, they might spread these germs to other countries to try to hurt their enemies. This is very dangerous because the germs can spread very quickly and can affect a lot of people.
That's why many countries have rules saying that biowar is not okay. They want to make sure that people don't use these powerful weapons to hurt others. It's important to remember that biowar is very serious and not something to play with.