Lice are parasitic insects that originate from evolutionary paths that adapted them specifically to humans. They have been around for hundreds of thousands to millions of years, evolving from common ancestors shared with lice that parasitize other primates. Head lice, body lice, and pubic lice are the three types of lice that infest humans, each adapted to different areas of the body or clothing. Lice come from direct contact with an infested person or through contact with their personal items like clothing, hats, brushes, or bedding. Head lice are mainly transmitted through head-to-head contact, especially common among young children. Body lice spread typically through clothing, and pubic lice mostly through sexual contact or shared bedding or clothing. In summary, lice originally evolved alongside humans and other primates and now exist as species specialized to feed on human blood. They come to a person mainly through close physical contact or shared personal items, not from pets or environmental sources like water or seats.