The individual water molecule (on the left) is composed of two hydrogen atoms and one oxygen atom.
The oxygen end of the molecule is negatively charged.The two hydrogen atoms bear a slight positive charge.
This separation of charge within the molecule is called "polarity", and the molecule is said to be "polar". Because
water is a polar molecule, it "sticks" to itself and has special properties. The positive end of one molecule is
electrically attracted to the negative end of another water molecule. (Courtesy: Michael J. Pidwirny)