1. Ionic bonds: These bonds form when one atom donates an electron to another atom, creating oppositely charged ions that are attracted to each other. This typically occurs between metals and nonmetals. For example, sodium chloride (NaCl) is held together by an ionic bond.

2. Covalent bonds: These bonds form when two atoms share electrons. This type of bond occurs between nonmetals. For example, the water molecule (H2O) is held together by covalent bonds.

3. Metallic bonds: These bonds form between metal atoms. In a metallic bond, electrons are delocalized and can move freely throughout the metal lattice, creating a "sea of electrons." This explains why metals are good conductors of heat and electricity.

While these are the three main types, it's worth noting that there are also other, less common types of bonds, such as hydrogen bonds and van der Waals forces. These are considered weaker than the main three types but play important roles in biological systems and other aspects of chemistry.