when 2 atoms combine by sharing electrons , its a covalent bond.
Covalent bonds are formed by non metals that share their valence electrons to complete the octet rule. Octet rule is when the atoms have 8 electrons in the outermost shell, atoms with complete octet in their outermost shells are stable. THerefore to become stable atoms tend to complete their outermost shell electrons. Covalent bonds are one way of completing the octet by sharing electrons
the othe type of bond is ionic bonding. Electrons are transferred from a metal element to a non metal element thereby completing the octets in both atoms. Here the electrons are transferred, donated by one atom and taken in by another
the answer for the question is covalent bonds