## 4 Results and Discussion
### Emerging Digital Payment Technologies
#### 4.1.2 E-Payments  
E-payments or electronic payments are generally known as payment technologies that do not involve physical cash, bank drafts or cheques [9] and the transactions usually take place through using internet services. It can also refer to the banking products and services that are being delivered to customers automatically via the internet [85]. In this study, e-payment and mobile payment technologies are categorized differently (see Figure 2 and Table 5). E-payment technologies refer to online payments that may or may not use mobile devices to complete transactions, whereas mobile payments use mobile phones for transactions. E-payments can be accessed either online through an e-payment website or online applications using, e.g., a laptop, tablet or desktop computer, while a mobile payment technology can be installed on a mobile device as an application and allows for \"tap to pay\" while shopping, often using an NFC chip. The payment through mobile payment technologies is normally made by tapping a POS machine (contactless payments) or scanning a QR code with a mobile phone. In general, mobile payment technologies can be seen as part of e-payment technologies. Some digital payment technologies (e.g., Google Wallet, Apple Pay, Samsung Pay) can be classified as both E-payments and mobile payments. However, there are some mobile payment technologies specially designed for mobile phones. For instance, the Swish app in Sweden is only available for use on mobile phones (e.g., iPhone, Android Phone). Swish is not available for use on laptops or desktops. Therefore, it is necessary to have a separate payment mode on mobile payments, which is described in Section 4.1.3. As shown in (Table 5 and Figures 2 and 3), 22 studies out of 58 focused on e-payment technologies in countries, such as India, Sweden, Zimbabwe, Italy, Nigeria, Ukraine, Indonesia, China, Jordan and the UK. The emerging e-payment technologies found in these studies include SADAD, E-Wallets, electronic fund transfer, e-banking, eCheck, EFITOPS, PagoPA, \"The Belt & Road\" silk currency, OPERA (Google Wallet, Apple Pay, Samsung Pay), GoPay & OVO (Indonesia) and P2P fund transfer, etc. One of the most used e-payment technologies is the 'e-wallet', which uses electronic devices, such as computers or tablets or mobile phones,to carry out transactions. There is a notable increase in the use of e-wallets because of their relative advantages as compared to debit and credit card payments. Although an e-wallet works the same as card payments, it has attractive cashback functions, a reward system, more convenient and better security features and, unlike debit or credit cards, e-wallets do not charge transaction fees [62]. Another similar e-payment technology is the 'digital wallet' [53], where users can transact online by linking their bank accounts. Digital wallets use electronic devices, e.g., Apple Pay is only available on Apple devices and Samsung Pay is on Android, whereas PayPal is on both Apple and Android devices. Several factors influence the adoption of digital wallets, e.g., in India, the government's vision of transforming the country into a cashless economy triggered growth [53]. Contrary to the digital wallet and e-wallet, which are both online payment systems, OPERA is an offline payment system for digital cash transactions between peer to peer [66]. OPERA addresses the limitations of other e-payment systems in terms of maintaining the key features of offline cash payments. Through the use of a 'one-time readable memory' and digital token, it enables a standard offline digital technology, which is unique to digital cash [66]. The electronic device EFTPOS stands for Electronic Funds Transfer at Point-of-Sale terminal. EFTPOS assists in initiating the transaction between a customer's personal bank account and a merchant's account. The use of EFTPOS reduces the demand for cash and lowers the overall use of currency [16].