To say the heart is important to your body is like saying daytime is pretty bright. The pumping of your heart starts a whole process of sending oxygen and nutrients to your body's millions of cells. Without the heart to send oxygenrich blood on its way, the cells would die.
The heart is a powerful muscle that expands to allow blood to enter, then squeezes to push it off in another direction. It is located in the middle of your chest, between your lungs, and is protected by your ribcage. It feels like it's a little off to the left because the bottom points that way, and that's where the strongest squeezing takes place.
How does the heart keep clean oxygenfilled blood separate from blood carrying the waste back from cells? It's all about chambers.