The type of bond formed in a chlorine molecule (Cl$_2$) is a covalent bond. Since both chlorine atoms are non-metals with high electronegativity, neither can completely pull an electron from the other. Instead, each chlorine atom contributes one of its 7 valence electrons to form a shared pair of electrons. By sharing this pair, both atoms effectively achieve a stable electron configuration of 8 valence electrons (an octet), similar to a noble gas. Since one pair of electrons is shared, it is specifically a single covalent bond.