Multi-Level Marketing (Networking), the Ulimate Money Machine

Have you ever been to a great movie or a great restaurant and told a friend about it? That's called word-of-mouth advertising. Business love word-of-mouth advertising because it's much more effective than all the money they spend on any other form of advertising, promotion, or marketing. Network marketing is a way for business to leverage the power of word-of-mouth advertising.
Let me give you a hypothetical example. Suppose you recommend a great restaurant (Let's call it ROD's Restaurant) to your sister. Your sister and her husband make a reservation for dinner and, during the meal, the waiter asks them how they heard about ROD's Restaurant. They mention your name. How would you feel if the owner of the restaurant sent you a thank you letter and a coupon for a free meal in appreciation for your recommending his restaurant? It would probably make you fell wonderful. The restaurant owner also explains in the letter that because of your recommendation, ROD has gained a new long-term customer. This customer didn’t result from ROD's Yellow Pages ad or it's radio and newspaper campaign. Therefore, the owner wants to reward you for this new word-of-mouth customer. Anytime your sister visits his restaurant in the future, he will send you a check for 10% of the value of the meal as a continuing thank you. Sure enough, every several months you receive a small thank you check. You're so impressed that you encourage others to visit ROD. This generates more free-meal coupons plus more 10% word-of-mouth checks. After a year, you are receiving small checks each month. After several years, you've help to create dozens of monthly customers, which generates hundreds of dollars of extra, no hassle income to you. That would be nice, wouldn’t it?

Excerpt from the book of Robert Allen's Multiple Stream of Income