Asthma is when your lungs have a tough time breathing in air. Your lungs are like little balloons that help you breathe. But sometimes, when you breathe in certain things like dust or pollen (tiny things from plants), or when you run around too much, your lungs might get scared or angry. Then, they start to swell up on the inside and it becomes hard to breathe.
Imagine your lungs are like a straw. When you breathe in air, it goes in easily like when you suck a drink through a straw. But when you have asthma, it's like someone is squeezing the straw really tight. This makes it hard for you to get air in and out of your lungs.
People with asthma might also get a cough, or their chest might feel tight. Sometimes they might even start to wheeze, which means make a whistling noise when they breathe.
It's important for people with asthma to take their medicine and avoid things that might make their lungs angry, like being around smokers or furry pets if they are allergic. This can help keep their lungs happy and healthy.