Differences among covalent, ionic and hydrogen bonds?

A covalent bond is formed when two atoms share electrons. An ionic bond is when one atom "steals" an electron from another, and the opposite electrical charges attract each other. Hydrogen bonds are somewhere in between. The oxygen part of a water molecule, for instance, shares its electrons with the two hydrogens, but they tend to stay around the oxygen atom more. This creates a polar covalent bond in which the oxygen has a slight negative charge and the hydrogens have a slight positive charge. Hydrogen bonding occurs between the slight negative charges and slight positive charges between two molecules.