What is an exponential growth?

From the statistics dictionary "

A function of a real variable defined for all real x by the sum to infinity of the (convergent) series
ex=1+x+x2/2!+x3/3!+.... The notation reflects the index property that ex×ey=ex+y. The notation 'exp(x)' is sometimes used for ex, particularly when x is a complicated algebraic expression. The number e is given by the above series with x=1, so
e=1+1+1/2!+1/3!+...≈ 2.718 28. The exponential and http://www.answers.com/topic/natural-logarithm functions are related by exp (ln x)=x for x>0 and ln (ex)=x for all values of x."

This link on answers.com has a 5 minute video which explains rxponential growth