There are generally three forms of head lice that you should be aware of: the nit (egg), nymph and the adult.  Head lice can spread very easily especially when people are in close contact.  Common ways to spread head lice are through direct hair-to-hair contact or by sharing certain things as hair brushes/combs, hats, headphones, hair bands, basically anything that may come in contact with your hair.  Head lice do not fly nor can they be transferred to pets. There are several products and home remedies that have been proven to work.