The Mole Chart
Core concepts in Science Chart explaining the Mole

The mole is also called the Avogadro constant

A brief explanation quoted from wikipedia, 25th January 2010:

In chemistry and physics, the Avogadro constant (symbols: L, NA) is the number of "elementary entities" (usually atoms or molecules) in one mole, that is (from the definition of the mole), the number of atoms in exactly 12 grams of carbon-12. It was originally called Avogadro's number. The 2006 CODATA recommended value is:

    N_{ m A}=6.022 141 79(30) imes 10^{23} mbox{mol}^{-1}

The Avogadro constant is named after the early nineteenth century Italian scientist Amedeo Avogadro, who, in 1811, first proposed that the volume of a gas (at a given pressure and temperature) is proportional to the number of atoms or molecules regardless of the nature of the gas. The French physicist Jean Perrin in 1909 proposed naming the constant in honour of Avogadro.  Perrin would win the 1926 Nobel Prize in Physics, in a large part for his work in determining the Avogadro constant by several different methods.

More info at:
http://en.wikipedia.org/wiki/Avogadro%27s_number