An ionic bond is a type of chemical bond formed by the electrostatic attraction between oppositely charged ions. This occurs when one or more electrons are permanently transferred from one atom to another, creating two oppositely charged ions. The positive ion is called a cation, while a negative ion is called an anion. The attraction between the positive and negative ions holds the ionic compound together.

For example, sodium chloride (NaCl) is an ionic compound formed by the transfer of one electron from sodium atom to a chlorine atom. This results in the formation of Na+ and Cl- ions, which are held together by the electrostatic forces between them.

Ionic bonds are typically formed between metals and non-metals. The metal atoms lose electrons to become cations, while the non-metal atoms gain electrons to become anions. The strength of an ionic bond depends on the charges of the ions and the distance between them.