The force that binds different atoms in a molecule (or ion) together is called chemical bond.
Bonding is explained by means of octet rule.
Octet rule:
Atom with eight electron in their outermost shell has maximum stability (like noble gas).
Types of Bond:
1. Ionic bond: Formed by the complete transfer of electrons.
2. Covalent bond: Formed by the mutual sharing of electrons.
3. Coordinate covalent bond: Formed by the donation of electron pair from one of the bonded atom.