What type of bond is formed when two atoms share electrons?

The bond formed when two atoms share electrons is known as a covalent bond. In a covalent bond, the atoms involved achieve a more stable electronic configuration by mutually sharing their valence electrons. This sharing allows each atom to attain the electron configuration of a noble gas, which is typically associated with chemical stability.

Covalent bonds can be classified into single, double, and triple bonds depending on how many pairs of electrons are shared between the atoms. For instance, in a single covalent bond, one pair of electrons is shared.

In contrast, an ionic bond occurs when electrons are transferred from one atom to another, resulting in the formation of ions. Metallic bonds involve a "sea of electrons" that are delocalized among a lattice of metal atoms, allowing for properties such as conductivity and malleability. Hydrogen bonds, while crucial in various biological processes, are weak attractions between molecules rather than bonds formed between atoms sharing electrons.

Therefore, the sharing of electrons between atoms distinctly defines the formation of a covalent bond, making it the correct answer.