Here's why:

* Carbon's Bonding Ability: Carbon has the unique ability to form four covalent bonds with other atoms, including other carbon atoms. This allows for the creation of long, complex chains and rings, forming the backbone of many organic molecules.

* Diversity of Functional Groups: Carbon can bind with various other elements like hydrogen, oxygen, nitrogen, and sulfur, creating functional groups that give organic compounds their diverse properties.

* Vast Number of Compounds: The ability of carbon to form so many different bonds leads to the existence of millions of known organic compounds, ranging from simple molecules like methane to complex biomolecules like proteins and DNA.

While other elements are present in organic compounds, carbon is the defining element that makes them organic.