Head lice are tiny, parasitic insects that infest the scalp, feeding on human blood. They are highly contagious and spread through close contact or sharing personal items like combs or hats.

Common symptoms include intense itching, a tickling sensation, and the appearance of tiny white nits (lice eggs) on hair strands. Causes include direct contact with an infested person or their belongings. While not harmful, head lice are a nuisance and require treatment with medicated shampoos or other remedies to eliminate the infestation.