Ionic bonds are formed when an element loses electrons (usually a metal), and other elements gain these electrons(usually a nonmetal or the hydrogen). When the element loses electrons, it becomes a cation, an ion with a positive charge; and when the element gains electrons it becomes an anion, an ion with a negative charge.
The charge in the ions produces an electrostatic attraction between them, and that attraction is the force that gets them together in a bond.
