Pyramid scheme's are HIGHLY illegal. Here is the definition of it which I got from Wikipedia. The definition on the site is very accurate.
A pyramid scheme is a non-sustainable business model that involves promising participants payment, services or ideals, primarily for enrolling other people into the scheme or training them to take part, rather than supplying any real investment or sale of products or services to the public. Pyramid schemes are a form of fraud.
Pyramid schemes are illegal in many countries including Albania, Denmark, Australia, Brazil, Bulgaria, Canada, China, Colombia, Estonia, France, Germany, Hungary, Iceland, Iran, Italy, Japan, Malaysia, Mexico, Nepal, The Netherlands, New Zealand, Norway, the Philippines, Poland, Portugal, Romania, South Africa, Sri Lanka, Switzerland, Taiwan, Thailand, Turkey, the United Kingdom, and the United States.
These types of schemes have existed for at least a century, some with variations to hide their true nature, and many people believe that multilevel marketing is also a pyramid scheme.
* 1 Concept and basic models
o 1.1 The "Eight-Ball" model
o 1.2 Matrix schemes
* 2 Connection to multi-level marketing
* 3 Connection to Franchise Fraud
* 4 Notable recent cases
o 4.1 Internet
o 4.2 Others
* 5 In popular culture
* 6 See also
* 7 References
* 8 External links
 Concept and basic models
This article may contain original research. Please improve it by verifying the claims made and adding references. Statements consisting only of original research may be removed. More details may be available on the talk page. (February 2009)
A successful pyramid scheme combines a fake yet seemingly credible business with a simple-to-understand yet sophisticated-sounding money-making formula which is used for profit. The essential idea is that a "con artist" Mr. X, makes only one payment. To start earning, Mr. X has to recruit others like him who will also make one payment each. Mr. X gets paid out of receipts from those new recruits. They then go on to recruit others. As each new recruit makes a payment, Mr. X gets a cut. He is thus promised exponential benefits as the "business" expands.
Such "businesses" seldom involve sales of real products or services to which a monetary value might be easily attached. However, sometimes the "payment" itself may be a non-cash valuable. To enhance credibility, most such scams are well equipped with fake referrals, testimonials, and information. The flaw is that there is no end benefit. The money simply travels up the chain. Only the originator (sometimes called the "pharaoh") and a very few at the top levels of the pyramid make significant amounts of money. The amounts dwindle steeply down the pyramid slopes. Individuals at the bottom of the pyramid (those who subscribed to the plan, but were not able to recruit any followers themselves) end up with a deficit.
 The "Eight-Ball" model
Many pyramids are more sophisticated than the simple model. These recognize that recruiting a large number of others into a scheme can be difficult so a seemingly simpler model is used. In this model each person must recruit two others, but the ease of achieving this is offset because the depth required to recoup any money also increases. The scheme requires a person to recruit two others, who must each recruit two others, who must each recruit two others.
The "eight-ball" model contains a total of fifteen members. Note that unlike in the picture, the triangular setup in the cue game of eight-ball corresponds to an arithmetic progression 1 + 2 + 3 + 4 + 5 = 15. The pyramid scheme in the picture in contrast is a geometric progression 1 + 2 + 4 + 8 = 15.
Prior instances of this scheme have been called the "Airplane Game" and the four tiers labelled as "captain," "co-pilot," "crew," and "passenger" to denote a person's level. Another instance was called the "Original Dinner Party" which labelled the tiers as "dessert," "main course," "side salad," and "appetizer." A person on the "dessert" course is the one at the top of the tree. Another variant, "Treasure Traders," variously used gemology terms such as "polishers," "stone cutters," etc. or gems like "rubies," "sapphires," "diamonds," etc.
Such schemes may try to downplay their pyramid nature by referring to themselves as "gifting circles" with money being "gifted." Popular schemes such as the "Women Empowering Women" do exactly this.
Whichever euphemism is used, there are 15 total people in four tiers (1 + 2 + 4 + 8) in the scheme - with the Airplane Game as the example, the person at the top of this tree is the "captain," the two below are "co-pilots," the four below are "crew," and the bottom eight joiners are the "passengers."
The eight passengers must each pay (or "gift") a sum (e.g. $1000) to join the scheme. This sum (e.g. $8000) goes to the captain who leaves, with everyone remaining moving up one tier. There are now two new captains so the group splits in two with each group requiring eight new passengers. A person who joins the scheme as a passenger will not see a return until they advance through the crew and co-pilot tiers and exit the scheme as a captain. Therefore, the participants in the bottom 3 tiers of the pyramid lose their money if the scheme collapses.
If a person is using this model as a scam, the confidence trickster would make the lion's share of the money. They would do this by filling in the first 3 tiers (with 1, 2, and 4 people) with phoney names, ensuring they get the first 7 payouts, at 8 times the buy-in sum, without paying a single penny themselves. So if the buy-in were $1000, they would receive $8,000, paid for by the first 8 investors. They would continue to buy in underneath the real investors, and promote and prolong the scheme for as long as possible to allow them to skim even more from it before it collapses.
Although the 'Captain' is the person at the top of the tree, having received the payment from the 8 paying passengers, once he or she leaves the scheme is able to re-enter the pyramid as a 'Passenger' and hopefully recruit enough to reach captain again, thereby earning a second payout.
 Matrix schemes
Main article: Matrix scheme
Matrix schemes use the same fraudulent non-sustainable system as a pyramid; here, the participants pay to join a waiting list for a desirable product which only a fraction of them can ever receive. Since matrix schemes follow the same laws of geometric progression as pyramids, they are subsequently as doomed to collapse. Such schemes operate as a queue, where the person at head of the queue receives an item such as a television, games console, digital camcorder, etc. when a certain number of new people join the end of the queue. For example ten joiners may be required for the person at the front to receive their item and leave the queue. Each joiner is required to buy an expensive but potentially worthless item, such as an e-book, for their position in the queue. The scheme organizer profits because the income from joiners far exceeds the cost of sending out the item to the person at the front. Organizers can further profit by starting a scheme with a queue with shill names that must be cleared out before genuine people get to the front. The scheme collapses when no more people are willing to join the queue. Schemes may not reveal, or may attempt to exaggerate, a prospective joiner's queue position which essentially means the scheme is a lottery. Some countries have ruled that matrix schemes are illegal on that basis.
 Connection to multi-level marketing
Main article: Multi-level marketing
The network marketing or multi-level marketing business has become associated with pyramid schemes as "Some schemes may purport to sell a product, but they often simply use the product to hide their pyramid structure." and the fact while some people call MLMs in general "pyramid selling" others use the term to denote an illegal pyramid scheme masquerading as an MLM.
The FTC warns "Not all multilevel marketing plans are legitimate. Some are pyramid schemes. It’s best not to get involved in plans where the money you make is based primarily on the number of distributors you recruit and your sales to them, rather than on your sales to people outside the plan who intend to use the products."  and states that research is your best tool and gives eight steps to follow:
1. Find — and study — the company’s track record.
2. Learn about the product
3. Ask questions
4. Understand any restrictions
5. Talk to other distributors (beware shills)
6. Consider using a friend or adviser as a neutral sounding board or for a gut check.
7. Take your time.
8. Think about whether this plan suits your talents and goals
Some believe MLMs in general are nothing more than legalized pyramid schemes making the issue of a particular MLM being legal or not moot.
With that said linked to MLM's you need to be very careful with what network marketing (MLM) company you get involved with. Make sure you look at their product and see if it is really legit.