Asthma What Is Asthma?
Asthma is a chronic (long-term) condition that affects the airways in the lungs. The airways are tubes that carry air in and out of your lungs. If you have asthma, your airways can become inflamed and narrowed at times. This makes it harder for air to flow out of your airways when you breathe out.
About 1 in 13 people in the United States have asthma, according to the Centers for Disease Control and Prevention. It affects people of all ages and often starts during childhood. Certain things, such as pollen, exercise, viral infections, or cold air, can set off or worsen asthma symptoms. These are called asthma triggers. When symptoms get worse, you can experience an asthma attack.
There is no cure for asthma, but treatment and an asthma action plan can help you manage the condition. The plan may include monitoring, avoiding triggers, and using medicines.
Learn basic facts about what asthma is and how it affects your airways. 
What is Asthma?
You can find asthma guides, tip sheets, and other resources through the NHLBI’s Learn More Breathe Better® Asthma program.