A louse is a small, wingless insect that belongs to the order Phthiraptera. They are ectoparasites, meaning they live on the outside of a host, typically feeding on blood or skin. There are several types of lice, including head lice, body lice, and pubic lice, each adapted to specific areas of the human body. Lice are usually transmitted through close personal contact or sharing personal items like hats and combs. Infestations can cause itching and discomfort, but they are not known to transmit diseases. Treatment often involves special shampoos or lotions designed to eliminate these pests.