What causes a eye infection

I have conjuntderfightes beacuse I had gunt covering my eye so I cant see what the heck causes it?

Conjunctivitis is one of the most common and treatable eye conditions in children and adults. Often called pink eye, it is an inflammation of the conjunctiva, the tissue that lines the inside of the eyelid and helps keep the eyelid and eyeball moist: http://www.webmd.com/allergies/guide/conjunctivitis

conjunctivitis?!? be careful, it's quite easy to spread.

Conjunctivitus is quite serious if you also have asthma, because in worst case you can have a fit and stop breathing...

What caused it would be you being allergic to something, im allergic to cats (their fur) thats why I got it, because I was constantly rubbing my eyes, after I touched something the cat had!