What makes molds grow?

Why are molds a concern?
Is there a mold problem?
How can you tell if it is mold?
How much mold is growing?
How to clean mold?
Dealing with an ongoing mold problem.
Preventing mold.
Mold-Proofing your home, basement.
Mold-Proofing your home, bathrooms, kitchen, laundry.
Mold-Proofing your house, closets and bedrooms, exterior.
Should I have my house air tested for mold?
The air feels dry, can I humidify?
What advantages do HEPA vacuums provide?
Is vacuuming with a HEPA or externally exhausted vacuum cleaner recommended for serious mold problems only?
Where do you find a HEPA vacuum cleaner?

Molds will grow if we provide them with moisture and nutrients. If we keep things dry, molds do not grow.

High moisture levels can be the result of water coming in from the outside, through the floor, walls or roof; or from plumbing leaks; or moisture produced by the people living in the home, through daily activities like bathing, washing clothes or cooking. Water enters the building when there is a weakness or failure in the structure. Moisture accumulates within the home when there is not enough ventilation to expel that moisture.

Different kinds of molds grow on different materials. Certain kinds of molds like an extremely wet environment. Other kinds of molds may be growing even if no water can be seen. Dampness inside the material can be enough to allow them to grow.