Chemical bonds are the forces that hold atoms together in compounds. The main types of chemical bonds are ionic bonds, covalent bonds, and metallic bonds. Ionic bonds form when one atom transfers electrons to another, creating charged ions that attract each other. This type of bond typically occurs between metals and nonmetals. Covalent bonds, on the other hand, involve the sharing of electrons between atoms, usually between nonmetals. This sharing allows each atom to achieve a full outer electron shell, leading to stability. Metallic bonds occur in metals, where electrons are shared freely among a lattice of metal atoms, allowing for conductivity and malleability.