How do brokers profit from CFDs

Hello,
does anyone knows how des brokers make money from CFD trading?
I know they are getting the feed from somewhere, but what are they doing to make this profitable for them?

I guess this is a very basic question, but I will be glad to understand CFD better.

Thank you!

Hello SessionGreen,

CFD are a replicate from an INDEX and are created by your brokers (issued)
Your broker will be the counter-party of all your trade as a Market Maker. There is no market just as the CME, it is only a virtual market between you and your broker
You buy --> your broker sell to you


How the broker can make money out of CFD:
- spread
- negative swaps on the long-side (if you hold position on the long-side, you will have to pay some swap overnight to your broker)
- thorough analysis of the trader profile and his strategy, if he is a winning machine, then the broker will have to hedge those trades, or he also can replicate those trades with other brokers
- if the trader seems inexperienced and impulsive, then just wait for him to blow-up

Brilliant answer.
Basically no difference with currencies.

Thank you ChanhXanh!
you made it clear and simple!