Mildew is a type of fungus that be found growing on a multitude of surfaces where moisture and temperature levels are high. Mildew can be identified and distinguished from other types of fungi by its thin, sheet-like appearance that often coats entire surfaces.
Mildew can be black or white in color.
As mildew grows, it leaves behind a musty, sour-like odor. Most mildews are caused by an overgrowth of it's close cousin, mold. In the home, mildew can grow on most types of fabric, leather, wood, paper, cement, linoleum, paint, sheet rock, and more. Low or non-existent lighting. Warm, humid temperatures.