Why does G-d have so many names?

The Torah and Tanach refer to G-d thousands of times but switches between many different names for G-d. Why does G-d have so many names, what do they each mean? How do we know which name of G-d to use? When do we pronounce and correctly spell G-d's name and when are they mispronounced and misspelled? 

A fascinating discussion about G-d's various names, what they all mean and how they are used.