Apple's mobile payment and digital wallet service - Apple Pay - can be used in more than 2 million locations.

Mobile payment system has changed the way people make payments for their purchases. Apple Pay allows people to make payments via their compatible iPhones, Apple Watch and iPads.

"Paying in stores or within apps has never been easier or safer. Gone are the days of searching for your wallet. The wasted moments finding the right card. Now you can use your credit cards, store credit cards, and rewards cards with just a touch," says Apple. "Apple Pay is simple to use and works with the cards you already have on the devices you use every day."

Apple Pay was initially released in October 2014 in the U.S. The service is now available in other countries such as the United Kingdom, Australia, Canada and more. In December 2015, the company announced that Apple Pay will be available in China starting February 2016.

"China is an extremely important market for Apple and with China UnionPay and support from 15 of China's leading banks, users will soon have a convenient, private and secure payment experience," said Eddy Cue, senior vice president of Internet Software and Services at Apple.

The growing popularity of mobile payment has led to the increased usage of services such as Apple Pay. According to a report, Apple Pay is now accepted in more than 2 million retailers, surpassing Apple's own target of 1.5 million retailers at the end of 2015.

At launch, Apple Pay was available only at a limited number of popular retailers. However, more and more partners are now accepting Apple Pay. Currently, customers can make payments via Apple Pay in McDonalds, Whole Foods, Disney theme parks, Best Buy, Kohl's, Macy's, Office Depot, Subway, Staples and more.

Online retailer Zappos.com has enabled Apple Pay on its mobile app and other merchants such as Crate & Barrel, Au Bon Pain and Chick-fil-A are estimated to roll Apple Pay support in their stores soon.

Aki Iida, the head of mobile at Zappos, says that the company added support for Apple Pay after receiving requests from customers.

Although, the popularity of mobile payment is growing, many people are still reluctant to use the service. In October 2015, 16.6 percent of people who owned Apple Pay compatible iPhones used the service, which is an increase from 9 percent in November 2014.

Expansion of the services in more countries and getting more merchants on board may help Apple to attract more iPhone owners to use Apple Pay as a mode of payment.