Why do people use diatomaceous earth?

Diatomaceous earth has many different uses. It is used as an organic pesticide, as a de-wormer, for flea control, for parasite removal, for grain storage, as a shoe shine, and many other applications. The type of diatomaceous earth that is used in these applications would be the food grade type.

There is a pool grade type but it is only used in swimming pools, never for humans or animals.