Successful growth investing often comes down to identifying which industries are poised to boom. And out of all the growth markets in the world at the moment, few are more promising than e-commerce.

Global retail e-commerce sales will exceed $6.5 trillion by 2023, according to Statista, up from $3.5 trillion in 2019. Those sales are largely going to be handled or made by a select group of companies.

Here are five companies that can help you as an investor in them claim your share of this massive and rapidly expanding market.

An upwardly sloping line labeled e-commerce is drawn above stacks of wooden blocks rising in a stair-step manner.

These stocks will help you profit from the incredible growth of e-commerce. Image source: Getty images.

1. Visa and 2. Mastercard

When investors think about e-commerce stocks, they often overlook Visa (NYSE:V) and Mastercard (NYSE:MA). That's a mistake. Many online purchases are made with credit and debit cards, and Visa and Mastercard operate the two largest card processing networks in the world. That makes them particularly well-positioned to profit from the surging growth of e-commerce.

Like an online toll road, Visa and Mastercard collect a small fee each time someone uses one of their cards to make an online transaction -- and the number of times this happens is soaring. U.S. e-commerce spending climbed 93% year over year in May, according to Mastercard. 

Moreover, Mastercard's global study showed that consumers around the world are increasingly shifting away from cash and toward contactless digital payments. Thanks to their powerful position atop the online payment processing industry, Mastercard and Visa stand to benefit from these megatrends more than any other business.

3. PayPal

Like the credit card giants, PayPal (NASDAQ:PYPL) is helping to enable online purchases. PayPal makes e-commerce sales easier, faster, and more secure, by removing the need for shoppers to enter their payment information each time they buy something online. By saving shoppers time and effort, PayPal also helps to boost merchants' sales conversion rates and, by extension, the profitability of their online stores.

PayPal's stock is also an excellent way to invest in the explosive growth of peer-to-peer payments. PayPal owns Venmo, the fast-growing mobile payment app that lets people easily and quickly send money to other Venmo users. Mastercard's study makes it clear that the coronavirus pandemic is accelerating the growth of digital cash transfers, and PayPal, thanks in part to its ownership of Venmo -- is offering you another great way to profit from this trend.

4. Shopify

While COVID-19 is fueling e-commerce growth, it's had a devastating impact on a huge swath of the traditional retail industry. In turn, many formerly brick-and-mortar merchants are turning to Shopify (NYSE:SHOP) to shift their businesses online. Shopify gives small -- and, increasingly, large -- businesses nearly all the tools they need to build and grow their online operations.

Shopify recently struck major partnership deals with Facebook, Walmart, and Chipotle -- all of which should help to fuel its expansion. More than 1 million merchants already depend on Shopify to power their online businesses, and with some of the largest and most powerful companies now coming aboard, even more merchants are likely to flock to Shopify's platform.

5. Amazon.com

It's difficult to make a list of the best e-commerce stocks to buy without mentioning Amazon.com (NASDAQ:AMZN). The online retail titan dominates many e-commerce markets around the world. Amazon, therefore, is poised to harvest the lion's share of the industry's profits in the decades ahead.

Better still, like the other stocks on this list, Amazon gives its shareholders many ways to win. Cloud computing and digital advertising are just a few of the massive industries in which Amazon has built a powerful presence, and it's likely to enter more new markets in the coming years. Amazon's stock thus gives you a way to profit from the expansion of multiple growth markets, making it an investment that's likely to pay off handsomely for you and other long-term investors.