Here's why:

* Organic Molecules: Carbon is the backbone of all organic molecules, which are essential for life. These include carbohydrates, lipids, proteins, and nucleic acids.

* Building Blocks: Carbon's ability to form four bonds allows it to create complex and diverse structures, providing the foundation for the vast array of molecules needed for life.

* Found in all Life Forms: From the simplest bacteria to complex humans, all living organisms utilize carbon in their biological processes.

While other elements like hydrogen, oxygen, nitrogen, and phosphorus are also crucial for life, carbon is the defining element that makes something biotic.