Asthma is an inflammatory condition of the lungs that makes it difficult to breathe. Asthma is chronic, meaning that inflammation is always present, even when there are no noticeable symptoms.
When provoked by a trigger the inflammation worsens, the insides of the airways produce extra mucus and the muscles that wrap around the airways may tighten, making the airways smaller and reducing the amount of air that can move in and out of the lungs.
Triggers include viral infections, allergies, irritating gases and particles in the air. Each person reacts differently to common asthma triggers.
There are different classifications of asthma to help pinpoint what is causing your asthma attacks. The American Academy of Allergy Asthma and Immunology (AAAI) has described the different types of asthma.