Are pin worms harmless?

I have a few questions about pin worms.
1. are they life threatening
2. do they go away on their own
3. what causes them
4. can they hurt you

I've heard that they are fairly common, harmless, and go away on their own... is this true? any help would be apperciated, thanks.

Pin worms are harmless and will never be life threatening. They will go away on their own,but will most probably return as you can reinfect yourself.

dont mess with anacondas, specially cobras

Except in very rare cases, they are harmless, and eventually go away on their own, if you don't reinfect yourself...
CAUTION: Yucky science facts ...

Pin worms live in your intestines. After they mate the female migrates to the host person's anus and lays her eggs on the outside around the anus, and secretes an itching agent there. The host often responds by scratching there, and subsequently transfers the pinworm eggs (which can live for 2-3 weeks on the outside) back to his mouth either directly or after touching food and eating it. It is very common for young children to repeatedly reinfect themselves. It is estimated that 100% of the population has been infected at one time or the other.
The test for the presence of pinworms is sometimes called the "scotch-tape" test. I'll let you look that up on your own.
Pinworms are gotten rid of with an over the counter medicine called Pin-X, followed by good hygiene.

pin worm is nocturnal worms, it cause itchiness at night.

ok thanks to all of you who helped