Pediculus humanus capitis, commonly known as head lice, are tiny parasitic insects that infest the human scalp. They feed on blood and can cause itching and discomfort. Head lice are most commonly found in children, but they can affect anyone with hair. They are spread through close contact and sharing personal items like hats or combs. Head lice are not known to transmit diseases, but their presence can lead to secondary infections from scratching. Treatment typically involves over-the-counter or prescription shampoos and thorough cleaning of personal items and living spaces to prevent reinfestation.