What is the difference between ionic, covalent and metallic bonding?

Ionic bonding occurs when transfer of electrons takes place. One atom (or molecule) donates one or more electrons to another. Since electrons have a negative charge, this leaves the donating atom electron deficient (+ve charged ion) and the other atom electron rich ( -ve charged ion). The ions then attract each other through electrostatic forces of attraction as they are oppositely charged. Covalent bonding occurs when atoms/molecules share pairs of electrons.Metallic bonding is bonding that occurs in metals. This leads to giant structures of metal atoms arranged in a regular pattern. The outer shell electrons of metals are delocalised (free to move around) and so a metallic structure is a regular arrangment of +ve charged ions with negative electrons in between, held together by electrostatic forces of interaction.