Pyramid Selling Scheme
Pyramid selling schemes normally involve members paying a joining fee and being promised they can recoup their sign up fee (and much more) by persuading their friends, family and strangers to join them.
Pyramid selling is illegal. Such money circulation schemes are guaranteed to fail because fresh income can only be generated by the organisation from finding new members to join.
Eventually, the whole population of the world will need to sign up to keep the scheme operating. When new members become difficult to find, recent members who've paid their sign up fee find they're getting nothing back in return. The scheme then collapses causing a lot of tears.
Legitimate franchising operations and network marketing schemes are not pyramid schemes and should not be confused with these dubious plans. If you have concerns about something you're offered, ask yourself, is there a product being sold?
If there isn't and you're being promised riches for doing little, get a grip of yourself and watch out!