Which bond type is primarily characterized by electron sharing between non-metals?

The bond type characterized primarily by electron sharing between non-metals is the covalent bond. In a covalent bond, non-metal atoms attain stability by sharing pairs of electrons, which allows them to fill their outer electron shells. This sharing can occur in various ways, resulting in single, double, or even triple bonds, depending on the number of electron pairs shared.

This bond type contrasts with ionic bonds, which involve the transfer of electrons from one atom to another, leading to the formation of charged ions. Metallic bonds, on the other hand, involve a 'sea' of delocalized electrons surrounding positively charged metal ions, rather than sharing between specific non-metal atoms. Hydrogen bonds are weak attractions that occur between a hydrogen atom covalently bonded to a highly electronegative atom and another electronegative atom. They are not a bond type by themselves but rather intermolecular forces.

Thus, covalent bonding's defining feature of sharing electrons makes it the correct answer in the context of bonds formed primarily between non-metal elements.