Informal schemes exist under many different names depending on where in the world they were originally based. For example, pardna (from the Caribbean), susu (from Africa), chit (south Asia) and kou (Japan).
Regardless of the name, they are all types of Rotating Savings and Credit Associations (ROSCAs).
ROSCAs bring together a group of people who might share something in common. This is usually a geographic connection or a social bond.
You contribute a fixed amount of money regularly (usually every month) into a pot, over a specific period of time (usually 6 months to a year).
At the end of the fixed period during which each pot is built up, the entire pot goes to one of the participants. The recipient is decided according to the rules of individual schemes.
This can involve each person in the scheme taking it in turns, through a lottery or by a bidding system.