First, it's important to know where to look. Mold tends to prefer cold, dark, and moist spaces. You probably won't find it in your living room, but your attic and crawlspace are much more likely hiding spots.
Mold will grow in places with a lot of moisture, such as around leaks in roofs, windows, or pipes, or where there has been flooding. Mold grows well on paper products, cardboard, ceiling tiles, and wood products. Mold can also grow in dust, paints, wallpaper, insulation, drywall, carpet, fabric, and upholstery.
And that's not all. You might also find it in doorways, windows, heating and air conditioning systems. It enters your home either through the air or by being attached to other moldy items like old shoes or newspapers. Once it's there, it's difficult to get rid of.