Here's why:

* Covalent bonds involve the sharing of electrons between atoms.

* Carbon and hydrogen both have a relatively high electronegativity difference, meaning they have a similar tendency to attract electrons.

* This similarity leads them to share electrons rather than one atom completely taking an electron from the other (which would create an ionic bond).

This shared electron arrangement is what creates the strong and stable bonds that are characteristic of hydrocarbons and many organic molecules.