This gives people the ability to pay for one product or service and receive an additional product or service free of charge. This can be used by a retailer to help increase traffic through their doors, which will hopefully lead to additional spend and positive word of mouth.
This type of promotion or deal will often be seen in the FMCG space. You may receive a mobile offer or coupon that rewards your loyaltyby offering you the opportunity to buy a pizza and receive an additional one for free for example.
This popular mechanic can be explored with a number of variations such as buying one particular product and get another product free. The appeal of this mechanic is that it provides a high degree of value perception.