What is a contaminant?

How do I tell contamination from healthy mycelium?

What are common contaminants of the mushroom culture?

There is 'white fuzzy stuff' growing on the stipes of my mushrooms...

My mushroom caps turned brown-violet over night, are they contaminated?

Proper hand washing procedure [Rate]
Hand washing is the single most important means of preventing the spread of infection.

The stems of my mushrooms are bluish-greenish. Is it contamination?