Hair
In short
Hair consists of protein filaments that grow from small openings in the skin called follicles. It is a key feature that distinguishes mammals from other animals.
In plain words
Hair is made of a tough protein called keratin. It grows out of your skin to help protect your body and regulate temperature.
A simple example
Humans have thick hair on their heads and much finer, lighter hair on most of their bodies.
Why it matters
Hair provides essential protection for the skin and helps sense touch. It also plays a role in keeping the body warm.
Easy to mix up
Do not confuse hair with fur, which is typically much denser and covers the entire body of many mammals.