Here's why:

* Electronic Configuration: Carbon has an atomic number of 6, meaning it has 6 electrons. Its electronic configuration is 2, 4. This means it has 4 electrons in its outermost shell (valence shell).

* Tendency to Bond: Atoms tend to gain, lose, or share electrons to achieve a stable octet (8 electrons) in their outermost shell. Carbon needs 4 more electrons to achieve this stability.

* Bonding Capacity: Carbon can form 4 covalent bonds with other atoms to share its 4 valence electrons. This gives it a valency of 4.

This is why carbon forms the backbone of so many organic molecules, creating diverse and complex structures!