What is a Ponzi-Scheme? Quick explanation

What is a ponzi-scheme?
It is just another way for scammers,to run you out of money,way to steal them.
Im explaining it for all of you to beware that it is really easy to fall in it.

Ponzi scheme base is an amount of investors,which gets bigger and bigger-thats why it is usually easy to find out if some page is an ponzi,because they always have some affiliate campainings.
It is all about one thing: You get payed out of the money that newer investor have sent to the company.

So for example: I deposit there 10$,and i say 5 of my friends that there is a great website where i can make money.
5 of them deposit 10$,and every friend of mine refers 5 other people.

So i got payed back 20$,but from the money of people that my friends know,so it will fall in sometime.
It wont-the company will run out with money,and they won't withdraw it to any other people that have already invested.
This is the reason that all visualizations of ponzi is a pyramid-because simply,they earn more money per every person in the system ( every brick )