Mold is a type of fungus that can grow both indoors and outdoors. It is commonly found in damp, dark, or humid areas, and can grow on a variety of surfaces, including wood, paper, carpet, and food.
Mold spores are tiny and invisible to the naked eye. They are released into the air when mold is present, and can be breathed in. Mold spores can also cause allergic reactions and respiratory problems.
Mold growth is often the result of indoor air quality problems. Poor ventilation, high humidity, and water leaks can all lead to mold growth. In order to prevent mold growth, it is important to keep indoor air quality high and to fix any water leaks promptly.
Sources:
https://www.cdc.gov/mold/faqs.htm
https://www.epa.gov/mold/mold-basics
https://www.mayoclinic.org/diseases-conditions/mold-allergy/symptoms-causes/syc-20351713