Your organs are what make you who you are, and they run every body process you need to live. They aren’t just parts inside you, like your liver or lungs. They also include parts on the outside of your body, like your eyes and mouth. But whether or not you can see them or realize they’re hard at work, they’re a key part of every day of your life.

Organs are specialized structures in your body that handle specific jobs. Some of the best-known organs are your heart, brain or liver. But many other structures count as organs, too. That includes some you might not think of, like your skin.

Each of your cells is like an individual worker doing a specific job. Tissues are groups of related cells teamed up in the same place. Organs consist of many tissues that work together cooperatively to accomplish a bigger job.

Organs are part of bigger systems that handle interconnected jobs. And some organs can be part of more than one system. Some examples of organ systems and the organs that are part of them include: