The heart is the muscular organ in your chest that pumps blood throughout your body, delivering oxygen and nutrients to every cell. About the size of your fist, your heart beats around 100,000 times each day without you ever having to think about it. When you run or get excited, your heart beats faster to pump more blood where your body needs it.

Beyond the physical organ, heart also describes courage, determination, and passion. When people talk about having heart, they mean showing these qualities in action. An athlete who never gives up has heart. A friend who stands by you during tough times shows heart. When you put your heart into something, you're giving it your full effort and enthusiasm.

The heart has symbolized emotions and character for thousands of years. When we say someone has a good heart, we mean they're kind and caring. When something breaks your heart, it makes you deeply sad. To take heart means to feel encouraged. To know something by heart means you've memorized it completely.

We also use heart to mean the central or most important part of something: the heart of a city, the heart of the problem, or getting to the heart of the matter when discussing something important.