Starting Monday, Oct. 20, Apple is rolling out its new Apple Pay mobile payment system to its latest iPhones, enabling shoppers to easily buy products at more than 220,000 stores.

Apple Pay aims to make it easy to pay for things using an iPhone and a fingerprint, facilitating the whole process and allowing for fast and secure payments. A number of companies are already on board, including McDonald's, Walgreen, Whole Foods, and others, but there are still notable players missing. Wal-Mart, for instance, is the nation's largest retailer, and is not part of Apple's network yet.

In fact, only a few have the necessary machines to read the near-field communication (NFC) radio signal on which Apple Pay is based, not to mention that checkout employees would have to be very familiar with the technology in order to properly assist customers. At the same time, only the latest iPhone 6 and iPhone 6 Plus smartphones come with NFC. The iPhone 5S, meanwhile, will work only when paired with the Apple Watch, but the smartwatch is not out yet.

Apple has struck deals with the six biggest card issuers, which make up roughly 83 percent of credit card transactions, and plans to add 500 more financial institutions by early 2015. The three major credit card networks - Visa, MasterCard, and American Express - are also on board with Apple Pay.

"Our team has worked incredibly hard to make Apple Pay private and secure, with the simplicity of a single touch of your finger," Eddy Cue, Apple's Senior Vice President of Internet Software and Services, said in a recent press release. "The reaction to Apple Pay has been amazing. We continue to add more Apple Pay ready banks, credit card companies and merchants, and think our users will love paying with Apple Pay."

"We are excited to make it easier and more convenient for our customers to shop at Whole Foods Market," added Walter Robb, co-CEO at Whole Foods Market. "We are thrilled to be one of the first retailers to accept Apple Pay across all of our locations nationwide as it offers our shoppers a fast, private and secure check out option at our stores."

While it all sounds quite promising, there are still a few notable hurdles to overcome. For now, neither credit cards nor prepaid cards are supported, nor are retailers' store-branded cards. This means that shoppers can't use their Bloomingdale's cards, for instance, with Apple Pay, which would make them miss out on some discounts.

In other words, Apple Pay still has a long way to go to become the ubiquitous payment system the company wants it to be, but it's on the right track. It remains to be seen how and when Apple will manage to overcome all hurdles, but it nonetheless seems promising. For more details regarding Apple Pay, head over to the company's website here.