You don't need to be a stock market genius to build wealth through equities. All it takes is time and patience -- and perhaps a few promising growth stocks, such as Square (NYSE:SQ) and NVIDIA (NASDAQ:NVDA).

Square is a leader in digital payments, while NVIDIA is the market share leader in graphics processing unit (GPU) suppliers.

Both companies have delivered market-beating returns for shareholders over the last five years, and both still have plenty of opportunities to expand. Here's why Square and NVIDIA are two growth stocks that can power your returns for many years.

A gigantic pile of dollar bills.

Image source: Getty Images.

Square: Massive opportunities in digital payments 

The adoption of mobile payments is an enormous opportunity. Cash is still the predominant form of payment around the world, but electronic transactions are rapidly gaining acceptance. Square is helping small businesses make the transition to a digital economy easier by offering things like digital checkout registers and software to manage inventory and payroll.

Square has already delivered a whopping return of 520% to investors over the last five years, but the company is just getting started. Square's current market cap (total shares outstanding times the stock price) is about $34 billion. Some investors might think the stock's valuation is too high, but one could argue it's actually on the low side when projecting out a couple of decades and envisioning Square making headway in international markets. 

Revenue growth has skyrocketed over the last few years, pointing to a tremendous runway for growth. Investors were disappointed with the company's outlook in the first quarter, but revenue growth of 39% year over year, excluding acquisitions, still looks terrific. After a sharp drop toward the end of last year, the stock price has bounced back in 2019, as investors recognize that Square is still a compelling growth story.

Based on ongoing momentum in the business, management recently raised the full-year guidance for revenue to be up 43% this year. Square hasn't reported a profit, but that's because of investments to fuel growth and expand the company's ecosystem of services. The more services the company offers small merchants, the stickier those services become, which widens Square's competitive moat.

Recent investments have resulted in the launch of the Square Card for merchants and other business management tools, such as Square Invoices as a stand-alone app. Analysts expect the Square Card to fill a massive void for small merchants who don't have a business credit card. Square Invoices, just one service on the company's menu, during the last year processed over $5 billion in gross payment volume with more than 350,000 active sellers. 

The company still has a lot of opportunities to expand. I wouldn't worry too much about valuation at this early stage of growth. Square has one of the most downloaded payment apps with the Cash App, and it continues to win over new merchants with a host of invaluable service offerings. This is a stock to tuck away for at least 10 years.

NVIDIA: The chipmaker that makes AI work

NVIDIA stock is up 784% over the last five years, even after its dramatic fall last year. The company known for making graphics processors for video gamers became a Wall Street darling early last year due to rising demand from cryptocurrency miners. NVIDIA also has experienced strong growth as a result of the strategy to expand its core graphics processing technology to a variety of applications across several industries.

While the demand in the gaming and data center segments slowed in recent quarters, there are secular trends in these markets that should get NVIDIA growing again.

The stock is up 27% year to date, as growth in the gaming segment -- which makes up most of NVIDIA's sales -- is slowly coming back. Sales of gaming graphics cards were up 11% sequentially last quarter. Driving the gaming segment is the momentum in the adoption of NVIDIA's ray-tracing graphics technology among game developers. Also, sales of gaming notebooks are exploding, and management sees sales of GeForce-powered laptops remaining robust through the end of the year. 

Although data center revenue slowed last fall and contributed to the stock's decline, the long-term opportunity in the data center is still there. Earlier this year, the company announced a $6.9 billion deal to scoop up Mellanox Technologies, an Israel-based company that specializes in high-performance interconnect technology in the data center space. The value of that deal is much larger than NVIDIA's annual data center revenue, which hints at the size of the opportunity in the data center market.

CEO Jensen Huang has a vision to transform every industry of the economy with its computing technology. The company is pushing into robotics, the automotive industry, as well as medical imaging. NVIDIA is working with Toyota Motor to develop, train, and validate self-driving cars -- a deal that could be huge given how widely the Toyota brand is represented on the road. Basically, any industry that is using artificial intelligence is a target for NVIDIA.

Alphabet's CEO Sundar Pichai has referred to artificial intelligence as "more profound than ... electricity or fire." Pichai's statement might sound outlandish at first, but NVIDIA is hoping he is on to something.

NVIDIA is at the center of this massive opportunity based on its leadership in high-performance computing. That's why you should consider adding the stock to your portfolio.