How does Wells Fargo (WFC ) make money? Well, they lend it out at a higher rate than they borrow it at. They’re a bank. There isn’t much more to it.

Alright, that isn’t much of an answer. Banking is the ultimate intangible industry, moving assets from lower-valued to higher-valued uses in the most impalpable of ways, but that still leaves plenty that distinguishes Wells Fargo from its major U.S. competitors. Starting with its size and its reach. Wells Fargo’s $272 billion market capitalization makes it the largest bank in the United States, and second in the world behind the Industrial and Commercial Bank of China. With branches in all but 11 states, Wells Fargo is one of America’s few truly national banking chains. (For more, see: The Banking Industry Handbook .)

Big, Regional Acquisitions

The bank as it’s currently comprised was created by a merger of large superregional banks. Founders Wells and Fargo created their namesake in 1852 to cater to the growing population of gold miners and related hangers-on in California, which back then was in the early stages of its transition from distant backwater to most populous and economically powerful state in the union. After close to a century and a half of steady growth, in 1998 Wells Fargo merged with Norwest Corp. headquartered in Minneapolis. A decade later, Wells Fargo bought out East Coast giant Wachovia. Add them all together, and Wells Fargo can now claim 70 million customers from coast to coast. (For more, see: Wells Fargo in Good Shape, But the Street Knows It and Wachovia-Wells Fargo: A Victory for All of Us .)

Officially, Wells Fargo divides its operations into three categories. In ascending order of importance those are wealth, brokerage and retirement; wholesale; and community.

Serving the Rich and the Mass Market

Wealth, brokerage and retirement means financial services for rich people. This end of Wells Fargo’s business doesn’t just dispense advice, e.g. on how to minimize taxes, but also helps set up foundations, solve inheritance issues before any might arise, etc. As any truly rich person knows, at least in the United States, preserving one’s affluence can be almost as much work as it was to get wealthy in the first place. The size of Wells Fargo’s wealth management operations place it 16th in the world among banks, far below industry heavyweights such as UBS AG (UBS ) and Credit Suisse Group (CS ), the institutions that normally come to mind when people think of banks that cater to elite clienteles. All told, Wells Fargo made $1.7 billion of profit off wealth management, brokerage and retirement in 2013. If that sounds substantial, it’s easily the least remunerative of the bank’s three areas of operations. And just another example of a phenomenon we see again and again: while it’s good business to sell to rich people, it’s even better business to sell to everyone else. Richard Marcus, heir to the Neiman-Marcus fortune, lives very comfortably. Alice Walton, daughter of Wal-Mart Stores, Inc. (WMT ) founder Sam Walton, could buy and sell Mr. Marcus several times over. (For more, see: How the Power of the Masses Drives the Market and How Wal-Mart Makes its Money .)

As for “wholesale,” that word has a slightly different meaning in banking than it does elsewhere. Plenty of banks don’t even use the term, but at Wells Fargo it’s a catch-all for underwriting. and selling asset-backed securities. along with other types of banking for large corporations and even other banks. (For related reading, see: How We’ll All Be Amazon.com Customers Eventually .)

Not Just Retail Banking

Actually, that doesn’t even begin to cover it. Wholesale banking includes, for instance, equipment financing. If you want to buy a dragline for your surface mining project, and don’t have the $35 million or so on hand to pay for it with cash, Wells Fargo can front you the money. Wells Fargo also handles crop insurance, commercial real estate, energy syndicated loans and more. Over 300 of the Fortune 500 companies do at least some wholesale banking with Wells Fargo. That’s when they’re not transferring their risk. Assuming you care, we’ll bet you didn’t know that Wells Fargo is the fifth-largest insurance brokerage in the world, too. (For related reading, see: How Warren Buffett Made Berkshire Hathaway a World-Beater .)

When a multinational with tens of millions of dollars in cash on its balance sheet needs somewhere to store that cash, Wells Fargo wholesale is where they do business. To be a Wells Fargo wholesale customer, you need annual revenues of at least $20 million. Wells Fargo’s wholesale operations have even greater reach than its community operations do. The bank has wholesale offices in 42 states, manned by 32,000 employees. That’s to say nothing of its wholesale offices across the globe, from Santiago to Seoul, Calgary to Cairo, and Sydney to St. Helier. All told, profits from wholesale banking totaled $8.1 billion last year, far more than wealth, brokerage and retirement operations.

Community Banking, Above All

Which leaves community banking, and hopefully it’s not too much of a spoiler to inform you that that’s where Wells Fargo is most successful. Community banking earned Wells Fargo $12.7 billion in 2013, on revenue of more than $50 billion. That margin might seem high, but it really isn’t. If you’ve ever been skeptical of how you can possibly be so big a profit center to a bank, what with your modest checking account balance and your restrained use of your debit card, understand that community banking is more than just ordinary people depositing their paychecks and maybe buying the occasional mortgage. To cite just one example, credit cards contribute hugely to Wells Fargo’s bottom line, as the people busy running up 5-digit balances ought to know. Wells Fargo boasts that its customers average more than six “products” per household, and wants to get that number up to eight. As far as Wells Fargo’s concerned, Shakespeare’s Polonius was right: neither a borrower nor a lender be. Instead, the bank would rather you took on both roles. (For related reading, see: A Look at Berkshire Hathaway’s Many Components .)

The Bottom Line

Wells Fargo’s profit margin on wealth, brokerage, and retirement banking is 13%, on community banking it’s 25%, and wholesale banking nets Wells Fargo 34%. Add it all up — on assets of $1.6 trillion — and it’s little surprise to find out that your humble little strip mall branch is just one cog in a juggernaut that continues to grow every year with little sign of abating. (For related reading, see: How Visa Counts on your Free-Spending Ways .)