Mold of any kind is not pleasant, but there is toxic mold called black mold that is very different from common household mold and mildew. It isn't always possible to identify toxic mold with the naked eye.
Toxic black mold is called Stachybotrys. It grows in damp area, such as basements or inside walls that have become wet or moist. This type of mold creates toxins that can affect the health of those who are exposed to it.
Common molds are cladosporium and aspergillus, both of which can be found in damp areas such as shower doors and curtains. This mold is not toxic but can cause allergies in some people. Food mold is called penicillium, which normally grow on cheese, fruit and many other foods.
Mold found in showers or shower curtains can be wiped off with bleach or other cleaning solution.
Mold--both black and household--normally begins growing in a building after some type of flood or perhaps a broken water pipe.
Never touch mold with bare hands--always use latex or rubber gloves. Any kind of black mold you see in your house needs to immediately be tested to ensure it is not the toxic form.