Final answer:
A covalent bond is formed when two neutral atoms share one or more pairs of valence electrons, creating a stable molecule with either a nonpolar or polar character based on the electronegativity of the atoms involved.
Step-by-step explanation:
When one or more pairs of valence electrons are shared by two neutral atoms, the type of bond formed is known as a covalent bond. This occurs when each bonded atom contributes one electron to a shared pair, creating a bond that holds the atoms together in a molecule. When electrons are shared equally it is a nonpolar covalent bond, but if one atom has a stronger pull on the electrons due to higher electronegativity, this results in a polar covalent bond. Covalent bonds can range from single bonds with one pair of shared electrons, as in H-H, to double or triple bonds with two or three pairs of shared electrons, respectively.