Loyalty programs are used by businesses to encourage customers to keep coming back. A review of 131 articles on loyalty programs found that most studies focus on why these programs work, like giving special status or making it easier to stick with a familiar brand. However, there's not much research on how loyalty programs work in online or business-to-business settings. The review also suggests that more research is needed on how loyalty programs compete with each other and how new technology affects how these programs are managed.