That's because you are actually Alphabet's product. The vast majority of the company's income -- $21 billion over the past 12 months -- comes from advertising revenue. By providing us with all of these amazingly useful things for no charge, Google aggregates a oceans of user information that helps marketers better target the right audience.

And Alphabet uses those massive profits to invest in even more innovation. The company is a leader in self-driving vehicle technology, clean energy, and connecting more of the world to the internet.

Image source: Microsoft.

3. Microsoft Corporation

Like Apple, Microsoft Corporation (NASDAQ: MSFT) played a big role in the advent of affordable personal computing. But while Apple developed a fully integrated software and hardware system, Microsoft is all about software. It also was a big reason why Apple lost the home PC wars in the late 1980s, while Microsoft, with its "Wintel" duopoly with Intel Corporation (NASDAQ: INTC) (which is also on this list) went on to command virtually the entire personal computer market for decades.

However, Microsoft has all but missed out on the smartphone revolution, with its Windows Phone never really garnering much commercial success. However, this lack of success with handheld devices hasn't kept Big Softy from being wildly profitable and still a growth company. After all, the company's operating systems and other software are still critically important to running the infrastructure that powers much of the world's computing power.

Microsoft has become a major player in cloud computing, a huge growth market. The company increased its market share last year, growing segment revenue 14% to $7 billion last quarter alone. Microsoft may have lost out to Apple in mobile computing, but it's not going to miss out on the cloud.

Image source: Getty Images.

4. Amazon

Amazon.com, Inc. (NASDAQ: AMZN) is one of few companies to emerge from the late 1990s tech bubble a success. And with a market cap of $560 billion, it easily qualifies as the biggest. Started by Jeff Bezos as an online bookstore, Amazon sells just about everything today, and tens of millions of people subscribe to its Prime membership program for free shipping, free TV, and free movie streaming. Prime members count on Amazon as their first -- and often only -- stop for online shopping. The company's sales are growing strongly: Last quarter alone, revenue was up 34% to $44 billion.

E-commerce isn't the only nascent industry Amazon is dominating, either. Amazon Web Services, or AWS, is the company's cloud computing provider, and Amazon commands substantial market share in this space as one of the lowest-cost providers. Last quarter, AWS generated almost $1.2 billion in operating income for Amazon, and it's set for potentially years of growth to come.

Image source: Getty Images.

5. Facebook Inc.

The dominant social media platform, Facebook Inc. (NASDAQ: FB), is worth $508.9 billion. Founded by CEO Mark Zuckerberg and several other Harvard students in 2004, it was initially available only to fellow Harvard classmates and then a few other colleges.

Like Google, Facebook doesn't charge its users a dime, instead making money -- $15 billion last year -- from advertising. And with more than 2 billion active global users, who share a lot of information about their lives and interests on the site, Facebook is a very compelling partner for marketers. How compelling? Consider this: Since 2015, Facebook has seen its market share grow from an already-absurd 74% to 79% of the market share of ad revenue spent on social networking sites in the U.S.

More than 26% of humanity regularly uses Facebook. That's a stunning figure, but it also means about three-fourths of us don't. Facebook's management would tell you that's room for growth.

Image source: The Motley Fool.

6. Berkshire Hathaway

Led by legendary investor and CEO Warren Buffett, Berkshire Hathaway Inc. (NYSE: BRK-A)(NYSE: BRK-B) is worth $468.4 billion. Since Buffett took over the company 50 years ago -- it was a struggling textile manufacturer at the time -- and converted it into a holding company for his various other investments, Berkshire has created enormous wealth for tens of thousands of shareholders.

Today, Berkshire is a sprawling conglomerate, with subsidiaries engaged in insurance, railways, candy making, manufacturing, electricity production, and too many other businesses to name here. Much of Berkshire's value also owes to its stock portfolio, which includes a number of the other companies on this list. At last count, Berkshire's stock holdings were worth about $180 billion, an amount that's likely to grow for years to come.

Alibaba founder and chairman Jack Ma. Image source: Alibabagroup.com.

7. Alibaba Group

Founded by executive chairman Jack Ma in 1999, Alibaba Group Holding Ltd (NYSE: BABA) started out connecting Chinese manufacturers to international buyers. Today, Alibaba Group is a lot more than that, having grown to become the e-commerce giant in China, with nearly 500 million active users over the past four quarters. Sales were up 61% last quarter, and the company expects revenue to increase as much as 53% for the full year.

Alibaba Group has rocketed up the top 30 list on expectations that its growth is just getting started. This year, the stock price has climbed 90%, even after a recent 9% drop. With China's middle class on track to crack 500 million people within a few years, Alibaba's best days could well be ahead.

Image source: Johnson & Johnson.

8. Johnson & Johnson

More than 130 years after its founding, Johnson & Johnson (NYSE: JNJ) is still one of the biggest innovators in the healthcare industry, as reflected by its $375 million market value. Best-known for consumer brands including Band-Aid and Tylenol, the healthcare giant is also a major medical device and pharmaceutical manufacturer. Last quarter, its pharmaceutical segment generated almost half of sales, while medical devices were worth twice as much revenue as the consumer-goods segment.

Looking ahead, JNJ's management is banking on the need for more healthcare spending as a significant portion of the world's population gets older. Life expectancies are increasing, but it will require significant medical support to care for a growing aging population. Even after 130 years of success, the company's future still looks bright.

Image source: JPMorgan Chase.

9. JPMorgan Chase & Co.

JPMorgan Chase & Co. (NYSE: JPM) has its roots as far back as 1799, with the founding of one of its predecessors, the Bank of the Manhattan Company. After dozens of acquisitions and mergers in the many years since, today's JPMorgan Chase is America's biggest bank, and one of the world's largest by total assets. It's worth $360 million at recent share prices.

Since the Great Recession, JPMorgan Chase, under the leadership of CEO Jamie Dimon, has built up a fortress-like balance sheet and developed some of the most conservative lending practices in the industry. So, even as one of the biggest banks out there, it is also considered one of the safest for investors to own.

Image source: Getty Images.

10. ExxonMobil

With a market cap of $348.6 billion, ExxonMobil Corporation (NYSE: XOM) is similar to JPMorgan Chase in that it's a product of numerous acquisitions and mergers over the years. It also has its roots in the early days of the American oil industry, directly descended from multiple companies that were part of John D. Rockefeller's Standard Oil.

A true integrated "supermajor," ExxonMobil participates in every aspect of the oil and gas value chain, including exploration and production, distribution, refining and chemical manufacturing, and selling refined products. Last quarter, this generated $66 billion in sales and $4 billion in profits -- better than recent quarters thanks to higher oil prices. But at the same time, there are growing concerns that the advent of cheaper renewable energy technologies and electric vehicles will start making fossil fuels irrelevant sooner than many expect.

Image source: Bank of America.

11. Bank of America

With a market cap of $295.7 billion, Bank of America Corp. (NYSE: BAC) is second to JPMorgan Chase among the most valuable U.S. banks. It's also the nation's second-biggest bank by assets as well.

Unlike many of its megabank peers, Bank of America's roots aren't in New York: The company started with the founding of the Bank of Italy in San Francisco in 1904 to serve the large immigrant community in the city, which faced discrimination by other banks at the time. By the late 1920s, Bank of Italy was renamed Bank of America and Italy, and it would merge with another California-based bank named -- you guessed it -- Bank of America.

Now headquartered in North Carolina, B of A was one of the banks hit hardest by the financial crisis, with two major acquisitions -- Countrywide Financial and Merrill Lynch -- leading to billions of dollars in losses, as well as tens of billions in fines and penalties related to Countrywide's mortgage practices. But today, Bank of America has emerged strong and profitable under the solid leadership of CEO Brian Moynihan.

Image source: Wal-Mart stores.

12. Wal-Mart Stores Inc.

Even as e-commerce becomes a bigger and bigger piece of the pie, brick-and-mortar behemoth Wal-Mart Stores Inc. (NYSE: WMT) remains a retail giant, with a market cap of $289.8 billion. Founded by Sam Walton in the early 1960s, Wal-Mart now operates more than 11,600 stores, it sold $486 billion in merchandise last year, and it employs 2.3 million people around the world.

And don't count the discount retailer out of the retail future, either. The company has aggressively invested in growing its e-commerce business, and it's paying off. Last quarter, Wal-Mart's e-commerce sales increased 50%, helping drive total sales up 4.2%. The "death of retail" may be grossly exaggerated, at least when it comes to Wal-Mart.

Image source: Wells Fargo.

13. Wells Fargo & Co.

The third bank to make the first half of our top 30, Wells Fargo & Co. (NYSE: WFC) makes the list at $279.3 billion. Founded in 1852 in San Francisco early during the gold rush, it not only offered banking services, but also express service to deliver gold and other valuables quickly. And while the modern Wells Fargo is the product -- like almost every big bank -- of numerous mergers and acquisitions over the years, its success has generally been a product of conservative management and lending practices that have kept it out of trouble during the numerous banking crises over the past 150-plus years.

But that story may be changing. More recently, Wells' results have trailed its peers' as the effects of the fake accounts scandal play out. Last quarter, Wells was the only big bank to report a decline in its revenue, and it also saw earnings per share fall more than 10% from the year-ago quarter. In short, there's evidence that customers are avoiding Wells, and choosing instead to bank with its competitors. Over time, it's likely that this will change as long as the company can get its act together. But in the meantime, its tarnished reputation is hurting its bottom line.

Image source: Getty Images.

14. Royal Dutch Shell plc

With a market cap of $271.9 billion, Royal Dutch Shell plc (ADR) (NYSE: RDS-A)(NYSE: RDS-B) is the second-most valuable public energy company on the U.S. market, behind only ExxonMobil. Also like ExxonMobil, Shell is an integrated supermajor, engaging in the full range of oil and gas industry businesses.

But Shell is a bit different from ExxonMobil in its strategy. Following its acquisition of BG Group in 2016, management launched a strategic shift toward natural gas, where it sees greater long-term demand growth versus oil. The company has also made reducing debt -- which ballooned to over $95 billion at the peak -- and expenses a priority, as well as taking steps to increase the return on its investments.

Shell has only just begun chipping away at its debt, but over the past year, profits and cash flows have surged on improved operating results, as well as higher oil prices. Shell is still exposed to many of the same risks as ExxonMobil when it comes to disruption from renewables, but that's one of the reasons management has prioritized natural gas, which produces fewer emissions and serves more industrial uses than oil.

Image source: Visa.

15. Visa Inc.

It may surprise you to know that electronic payments network giant Visa Inc. (NYSE: V), with a market cap of $249.8 billion, has only been a public company for about 10 years. Started in 1958 as part of Bank of America and called BankAmericard, it would not become a separate company until 1970, and even then, it was largely under the control of the many banks that issued BankAmericards.

In 1968, it would formally change its name -- and the name of the cards issued on its network -- to Visa, but it would remain privately held until finally going public in March 2008. Visa's IPO, which was for half of the company's shares, raised $19.1 billion, making it the biggest-ever IPO at the time.

Even with its massive size, Visa still has strong growth prospects. Electronic payments are only a small fraction of global transactions, but that's quickly changing as mobile computing and the global middle class converge. As a trusted name that merchants, financial institutions, and customers all count on, Visa is positioned for many more years of growth.

Image source: Procter & Gamble.

16. Procter & Gamble Co.

With a market cap of $226.8 billion, Procter & Gamble Co. (NYSE: PG) is one of the most valuable makers of branded consumer products in the world. There's a good chance you have at least one P&G product in your home right now -- and more likely several. The company's most recognizable brands include Bounty, Crest, Gillette, Pampers, Tide, and Vicks, but that's just a handful of the more than 60 brands the company makes and sells in over 180 countries.

Founded in 1837, the company has spent the past 180 years developing and acquiring products that people use in their daily lives, many of which were major innovations at the time. More recently, the company has struggled to grow, having already expanded into just about every global market, and also facing stiff competition in many of its core segments. This has led management to streamline its brands and focus more intently on its most important businesses. Since 2013, the company has reduced its brand portfolio by more than half.

Sales have fallen almost $15 billion since then, but earnings have improved since bottoming out in 2015. This is helping the company continue its track record of dividend growth. P&G has increased its dividend annually for 61 straight years.

Image source: Anheuser-Busch Inbev.

17. Anheuser-Busch Inbev

With a market cap of $224.1 billion, Anheuser-Busch Inbev NV (ADR) (NYSE: BUD) is the most valuable beer company on Earth. Commonly known as AB Inbev, the company may be best-known in the U.S. for its Budweiser products, but the world's largest brewer makes a lot more than Bud. The company owns and produces hundreds of different beers around the world, including seven of the 10 biggest brands.

Just how big is this megabrewer? You may want to sit down before you read this: About one in every three beers drunk on the entire planet came out of an AB Inbev brewery. In the world of beers, they just don't come any bigger than this company.

Image source: Getty Images.

18. AT&T Inc.

The biggest and most valuable telecommunications company on the U.S. market, AT&T Inc. (NYSE: T) is worth $224 billion. When Alexander Graham Bell founded AT&T in 1885, he probably didn't have any idea how much his company would transform over the next 130 years, while also staying remarkably the same. AT&T is still the largest provider of fixed-line telephone access in the U.S., but it's also the second-largest cellphone cellphone service provider, and the largest pay-TV operator in the U.S., through its U-Verse cable and DirecTV satellite subsidiaries.

The company is looking to get even bigger, with a pending acquisition for Time Warner (NYSE: TWX) in the works. However, the U.S. Department of Justice is threatening to sue over the proposed acquisition, creating some uncertainty (and a lot of drama thanks to the political implications).

Image source: Getty Images.

19. Chevron Corporation

The third integrated super-major on this list, Chevron Corporation (NYSE: CVX) is worth $222.6 billion. The company's roots go all the way back to 1879, with the founding of Pacific Coast Oil Co. in San Francisco and developing some of the state's earliest oil discoveries in Southern California. Coast oil would be acquired by Standard Oil in 1900 and consolidate its operations and take the Standard name in 1906.

In 1911, it once again became a separate company when the federal government's antitrust suit led to the breakup of Rockefeller's Standard Oil behemoth. Following decades of growth and expansion both in the U.S. and abroad, the company finally changed its name to Chevron in 1977 as part of its move to merge six domestic operations into one.

Today, Chevron is solidly profitable, but its earnings and cash flows are still far below its historical levels, as it just isn't getting the same kinds of returns on its investments at recent oil prices. However, its results have improved over the past year as oil prices have risen.

Image source: Getty Images.

20. UnitedHealth Group Inc.

With a market cap of $216 billion, UnitedHealth Group Inc. (NYSE: UNH) is the second-most valuable healthcare company and the most valuable health insurer and managed care provider in the United States. Founded in 1974 as Charter Med Incorporated, UnitedHealthCare Corporation was created in 1977 as the parent company and taken public in 1984.

In the 40 years since its founding, the Minnesota-based healthcare giant has steadily grown by expanding into new markets and acquiring companies in markets it wanted to enter. It also expanded its services to include prescription management and mail-order services, among others.

At last count, the company insures 49 million people, and it generated more than $50 billion in revenue and $4.1 billion in operating income in its most recent quarter.

Image source: Pfizer.

21. Pfizer Inc.

Pfizer Inc. (NYSE: PFE) is the third-most valuable healthcare company on this list, with a $215.8 billion market cap.

Founded by Charles Pfizer and Charles Erhart in New York City in 1849, Pfizer found early success as a so-called "fine chemicals" maker for most of the first century of its existence. In the early 1950s, Pfizer scientists would discover and develop the antibiotic Terramycin, one of the first steps that began shifting its focus to research and development of pharmaceuticals.

Over the past couple of decades, Pfizer has largely grown via acquisition of competitors including Warner-Lambert in 2000 and Wyeth in 2009, both of which have produced mixed results. Going forward, management continues to consider acquisitions to help augment its in-house R&D pipeline for new medicines.

Image source: Roche.

22. Roche Holding Ltd.

The third healthcare company in a row on this list, Switzerland-based Roche Holding Ltd. (ADR) (NASDAQOTH: RHHBY), is worth $214.5 billion. Founded in 1986 by young entrepreneur Fritz Hoffmann-La Roche, Roche's roots are in the industrial manufacture of medicines.

Fast-forward 130 years, and Roche is one of the leading biotechnology companies in the pharmaceutical industry, with a major pipeline of potential cancer treatments, including immunotherapies. Roche is also one of the biggest R&D; spenders in the healthcare space, having spent nearly $9 billion to develop new medicines and treatments last year alone.

Image source: Getty Images.

23. China Mobile

With nearly 875 million subscribers on its network, China Mobile Ltd. (ADR) (NYSE: CHL) is easily one of the world's biggest wireless providers, and it's worth $208.9 billion. One would expect it to carry a higher value, perhaps, due to its size and potential for growth. However, China Mobile -- and its biggest competitors -- are pretty much controlled by the Chinese government, which heavily regulates the wireless market in the country.

Even with that reality, China Mobile is likely to grow in value as China's middle class continues to expand and mobile use becomes more prevalent. Mobile data consumption is also likely to increase across both consumer and business customers in the coming years, and that could be a catalyst for further growth for the Chinese wireless giant.

Image source: Getty Images.

24. Home Depot

Founded in 1979 with the opening of two stores in metro Atlanta, Home Depot Inc. (NYSE: HD) is worth $207 billion, only trailing Wal-Mart for U.S. brick-and-mortar retailers in market value. It's also very different from Wal-Mart and other general merchandise retailers, with many of the products it sells being highly resistant to infringement from e-commerce. This includes products like lumber, which carpenters and builders often prefer to hand select, as well as items customers want to choose in person, such as tile, flooring, paint, cabinets, fixtures, and other big-ticket items you have to live with every day.

It's certainly played out that way. While many other big-box retailers struggle just to keep the doors open, Home Depot's sales have increased 6% so far this year, and earnings are on track to grow 14%.

Image source: Intel.

25. Intel

The other half of the "Wintel" duopoly with Microsoft that dominated personal computing for more than two decades, Intel Corporation (NASDAQ: INTC) was founded in 1968 and is worth $205.7 billion today, making it the the most valuable stand-alone semiconductor manufacturer in the world.

Also like Microsoft, Intel has had middling success in mobile computing while remaining incredibly strong in the data centers that drive cloud computing and corporate infrastructures. However, there's some concern that the company's fortress-like competitive position in the data center could be weakening. If that proves to be true, and competitors start taking market share, that would seriously crimp Intel's future prospects.

But with a half-century of successful innovation in microprocessors, and one of the biggest R&D budgets in the space, I wouldn't count Intel out just yet.

Image source: Getty Images.

26. Taiwan Semiconductor

Like Intel, Taiwan Semiconductor Mfg. Co. Ltd. (ADR) (NYSE: TSM) is a leader in the manufacture of microprocessors, and it has a similar market value of $204.4 billion. However, it's also a very different company, since Intel designs and develops nearly all of the processors it makes, while Taiwan Semiconductor primarily contracts with so-called "fabless" semiconductor designers -- companies like Apple -- to manufacture chips for them.

The upside is the company doesn't have to spend nearly as much on R&D -- it spent $11 billion less than Intel over the past year -- and instead focuses on high-quality, low-cost manufacturing while its customers invest in chip design. The downside? Maintaining a competitive advantage to keep those fabless chip designers coming to you for chip fabrication.

It's certainly worked well for Taiwan Semiconductor, which has seen its earnings and market value grow more than 250% over the past decade, better than Intel over the same period.

Image source: Verizon.

27. Verizon Communications

With a market cap of $203.6 billion, Verizon Communications Inc. (NYSE: VZ) is the second-biggest telecommunications company in the U.S. behind AT&T. Verizon leads the U.S. wireless market with 149 million customers, and it also has one of the biggest land-line operators. The company has also increased the size of its wireline internet business in recent years and says it now has 5.8 million customers using its Fios fiber-optic internet service.

But where Verizon trails AT&T is in pay-TV subscribers, a gap that's likely to grow even wider when AT&T completes its acquisition of Time Warner. Will Verizon make an acquisition of its own to narrow the gap? It's unclear, but the company is certainly investing in next-generation wireless technology, with plans to begin testing a 5G network in 2018.

Image source: Getty Images.

28. Oracle Corporation

Business software specialist Oracle Corporation (NYSE: ORCL) is worth $202.4 billion.

Like almost every other tech company that's been successful for many years, Oracle has spent decades out-innovating (or sometimes acquiring) its disruptors. In recent years, this has included a shift to subscription models for software -- something Oracle is still working through -- and now the company is facing stiff competition from the likes of Amazon and other cloud-computing providers.

Going forward, Oracle may have to prove its mettle all over again in the ever-important enterprise database segment it has dominated for years. The early results offer promise, but it's in the very early innings as the company's customers -- almost 40% of the market for enterprise database software -- begin to compare in-house systems to cloud-hosted alternatives.

Image source: Citigroup.

29. Citigroup Inc.

With a market cap of $198.4 billion, Citigroup Inc. (NYSE: C) is the last bank in the top 30 and the fourth-most valuable bank behind JPMorgan Chase, Bank of America, and Wells Fargo. With over 200 million global customers and 219,000 employees, Citigroup does business in 160 countries around the world.

With its roots in the founding of City Bank of New York in 1812, it underwent a series of name changes over the next 160 years before finally becoming Citibank in 1976. The current Citigroup was formed when Citicorp -- Citibank's holding company -- merged with Travelers Group in 1998.

Citigroup was one of the hardest-hit banks during the subprime crisis and Great Recession, with its significant exposure to bad mortgages -- both directly through its lending and through its investment in collateralized debt obligations -- which led to substantial losses, and eventually required federal government intervention to keep the bank from failing. This intervention and investment essentially wiped out investors in the company. Even after a pretty big recovery in the past decade, Citigroup investors from right before the financial crisis are still down about 75%.

On the other side of the coin, anyone savvy -- or lucky -- enough to have invested in the company in March of 2009 and held their shares has seen a fourfold return on their investment.

Image source: Novartis.

30. Novartis

Another Swiss pharmaceutical company on the list, Novartis AG (ADR) (NYSE: NVS) rounds out the top 30 with a market cap of $198.2 billion. But unlike Roche, which was founded more than a century ago, Novartis is the result of multiple corporate mergers, though several of its legacy companies do date back to the 1800s.

However, Novartis is similar to Roche in several regards. The company spent $7.9 billion on pharmaceutical research and development last year, second only to Roche in pharmaceutical R&D investment. Much of that spending is on development of biologics and immunotherapies, two of the areas of medicine with the most promise for treatments with fewer side effects and better results.

With expectations that the company will file for approval of five new molecules in 2018, Novartis's R&D investments seem to be paying off.

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John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. Suzanne Frey, an executive at Alphabet, is a member of The Motley Fool's board of directors. Teresa Kersten is an employee of LinkedIn and is a member of The Motley Fool's board of directors. LinkedIn is owned by Microsoft. Jason Hall owns shares of Alphabet (A shares), Amazon, Apple, Bank of America, Berkshire Hathaway (B shares), Facebook, Intel, and Royal Dutch Shell (B Shares). The Motley Fool owns shares of and recommends Alphabet (A and C shares), Amazon, Anheuser-Busch InBev NV, Apple, Berkshire Hathaway (B shares), Facebook, Johnson & Johnson, Verizon Communications, and Visa. The Motley Fool owns shares of Oracle and has the following options: long January 2020 $150 calls on Apple, short January 2020 $155 calls on Apple, short January 2018 $170 calls on Home Depot, and long January 2020 $110 calls on Home Depot. The Motley Fool recommends Home Depot, Intel, and Time Warner. The Motley Fool has a disclosure policy.