Lice are tiny insects that live on humans and feed on blood. They can't jump or fly, but they can spread easily from one person to another through close contact or shared personal items.
The main types of lice that live on humans are head lice, pubic lice (crabs), and body lice.
The main symptom of lice is itching. Scratching affected areas can make the skin raw, and these areas may get infected.