Can someone please explain the valence bond theory and are there any other bonding theories to explain how a bond is formed

Thanks for any help :)

More or less the valence bond theory is e- defficient atoms pairing off with atoms that can make up the difference. Its also called a covalent bond. Covalent bond are the bonds in compounds that result from the sharing of one or more pairs of electrons. For example NaCl (Na+) + (Cl-). Na is positive because its missing an e- which means that the atom is not neutral because it now has 1 more p+ than e-s. so it joins with Cl which by the way is negative. Because it has gained and e- and it shares with Na to make NaCl. Now its neutral and has no charge because now it has just as many e- as protons. Well something like that.