Albert Einstien called compound interest the 8th wonder of the world.

Compound interest is the addition of interest to the principal sum of a deposit, or in other words, interest on interest. It is the result of reinvesting interest, rather than paying it out, so that interest in the next period is then earned on the principal sum plus previously accumulated interest.

The 9th wonder is patience,  which most of the people on earth don’t have.

Trading is the purest form of compound interest, using past profits to trade slightly larger future trades and on and on.