Does anyone could tell me about Google Adsense (AdWork)

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Hi, I heard about such a program Google adsense and adwork. Please tell more about it. I search net how it works, but I think here you will explain me as simple as posible. Tell me if there is need for a real website or its just can be a blog or even facebook page. How all the principal in earning money can be with these programs. Thank you in advence.