A bank is a business that holds your money and lends it out to other people

A bank takes deposits from customers like you, keeps some of that money in reserve to cover withdrawals, and lends the rest to borrowers—homebuyers, businesses, people with car loans. The bank makes money on the difference between what it pays you in interest on your deposit and what it charges borrowers for loans. You get a safe place to store money and access it through checks, debit cards, and transfers. The bank gets to use your money to generate profit.

This arrangement has existed in roughly the same form for centuries. What has changed is the infrastructure: instead of walking to a teller window, you now move money through apps, ATMs, and electronic networks. The core transaction—you deposit, the bank lends, you earn a small return—remains the same.

Key Takeaways

  • Banks are for-profit businesses that accept deposits, hold them in accounts, and lend most of that money to other customers or investors.
  • The Federal Deposit Insurance Corporation (FDIC) insures deposits up to $250,000 per account holder per bank, so your money is protected if the bank fails.
  • Banks earn revenue by charging interest on loans and fees for services, then paying you a smaller interest rate on savings accounts.
  • Different types of banks—commercial banks, credit unions, online banks—operate under different rules but all perform the same basic function of holding and moving money.
  • Banks are regulated by federal and state authorities to prevent fraud, may support they hold enough capital, and protect depositors.

How a bank makes money from your deposit

When you deposit $1,000 into a savings account, the bank does not lock that money in a vault with your name on it. The bank pools deposits from thousands of customers and lends that money out. If you earn 0.01% annual interest on your $1,000 (which is typical for many savings accounts), you make about $0.10 per year. Meanwhile, a borrower taking out a mortgage might pay 6% to 7% interest. The bank keeps the difference—roughly 6% to 7% minus the 0.01% it paid you.

Banks also charge fees: monthly maintenance fees, overdraft fees, wire transfer fees, ATM fees if you use another bank's machine. These fees are a second source of revenue. A bank with one million customers paying an average of $10 per month in fees generates $120 million annually before lending profits.

This is why banks compete aggressively for deposits. More deposits mean more money to lend and more fee revenue. It is also why banks can afford to offer you free checking accounts—the money you keep there is worth far more to them than the cost of maintaining your account.

The difference between a bank, a credit union, and an online bank

Commercial banks are for-profit corporations owned by shareholders. They operate physical branches, employ thousands of people, and are regulated by the Federal Reserve, the Comptroller of the Currency, and state banking authorities. Examples include Chase, Bank of America, and Wells Fargo.

Credit unions are member-owned cooperatives, not corporations. When you open an account, you become a partial owner. Credit unions are smaller, often serve a specific community or profession, and typically offer lower fees and higher savings rates than commercial banks because they return profits to members rather than shareholders. They are regulated by the National Credit Union Administration (NCUA) instead of the Federal Reserve.

Online banks have no physical branches. They operate entirely through websites and apps, which means lower overhead costs. They often offer higher interest rates on savings accounts and lower fees than brick-and-mortar banks. Examples include Ally, Marcus, and Discover. Online banks are still regulated by federal authorities and insured by the FDIC, so your money is just as protected as at a traditional bank.

What FDIC insurance actually covers

The Federal Deposit Insurance Corporation (FDIC) is a government agency that insures deposits at member banks. If a bank fails—runs out of money and cannot pay depositors—the FDIC steps in and reimburses you up to $250,000 per account holder per bank. This limit applies per depositor, per insured bank, per ownership category.

That last phrase matters. If you have a checking account in your name at Chase and a savings account in your name at Chase, the FDIC covers both under the same $250,000 limit. But if you have $150,000 in your name and $150,000 in a joint account with your spouse at the same bank, each is covered separately—$250,000 for your individual account and $250,000 for the joint account. Money in a trust account, a retirement account (IRA), or a business account are also counted separately.

FDIC insurance does not cover investment accounts, stocks, bonds, or money market funds held at a bank's brokerage arm. It covers only deposit accounts—checking, savings, money market deposit accounts, and certificates of deposit (CDs).

How banks are regulated and what that means for you

Banks operate under a layered system of regulation. The Federal Reserve sets monetary policy and supervises large banks. The Comptroller of the Currency (OCC) charters and regulates national banks. State banking authorities regulate state-chartered banks. The FDIC insures deposits and also supervises banks. Credit unions are supervised by the NCUA.

These regulators require banks to maintain a minimum amount of capital—money held in reserve—relative to the loans they make. This prevents banks from lending out so much that they cannot cover unexpected losses or a sudden wave of withdrawals. Regulators also conduct audits, review lending practices to prevent discrimination, and enforce rules against money laundering and fraud.

For you as a customer, regulation means your bank cannot straightforward disappear with your money. It must hold enough capital to survive a crisis. It must report suspicious activity to law enforcement. It cannot charge you arbitrary fees without disclosure. And if something goes wrong, you have a path to dispute it—banks must investigate unauthorized transactions and resolve errors within specific timeframes set by federal law.

What happens when you deposit a check or transfer money

When you deposit a check, the bank does not when ready credit your account with the full amount. The check must clear—the bank that issued the check (the paying bank) must confirm that the account holder has sufficient funds and actually transfer the money. This process typically takes one to three business days, though some banks now offer next-day clearing for certain deposits.

When you transfer money electronically—via ACH (Automated Clearing House), wire transfer, or real-time payment systems like Zelle—the money moves through a network of banks and clearing houses. An ACH transfer usually takes one to two business days. A wire transfer typically clears the same day but costs $15 to $50. Real-time payment systems like FedNow (launched by the Federal Reserve in 2023) move money in seconds, though not all banks participate yet.

The delay exists because banks need time to verify the transaction is legitimate and that funds are actually available. During that window, the money is in transit—it has left your account but has not yet arrived at the destination. This is why banks can freeze accounts during disputes or investigations: the money is real, but its ownership is temporarily uncertain.

Why banks ask for so much personal information

Banks collect your Social Security number, address, employment history, and other details for three reasons: to verify your identity, to comply with anti-money-laundering laws, and to assess credit risk.

Identity verification prevents fraud. A bank must confirm you are who you claim to be before opening an account or processing large transactions. They do this by checking your information against databases maintained by credit bureaus and identity verification services.

Anti-money-laundering rules (enforced by the Financial Crimes Enforcement Network, or FinCEN) require banks to know their customers and report suspicious activity. If someone deposits $50,000 in cash every week without explanation, the bank must file a Suspicious Activity Report (SAR). These rules exist to prevent banks from being used to launder drug money, finance terrorism, or hide proceeds of crime.

Credit assessment is a business decision. If you explore for a loan or overdraft protection, the bank wants to know whether you have a history of paying debts. They pull your credit report and review your account history with them.

Frequently Asked Questions

What is the difference between a debit card and a credit card?

A debit card draws money directly from your bank account—you spend only what you have deposited. A credit card borrows money from the card issuer on your behalf; you receive a bill and must repay it. Debit cards do not build credit history. Credit cards do, but they charge interest if you carry a balance.

Can a bank refuse to open an account for me?

Yes. Banks can refuse service for any reason except those protected by law (race, religion, national origin, sex, age, marital status). They often refuse if you have unpaid overdrafts at another bank, a history of fraud, or if you cannot provide required identification documents. Some banks also use ChexSystems, a checking account history database, to screen applicants.

What happens to my money if the bank is hacked?

If a hacker steals your login credentials and transfers money out of your account, federal law requires the bank to reimburse you if you report the fraud within 60 days. The bank's security systems are also regulated—they must use encryption, multi-factor authentication, and other safeguards. FDIC insurance does not cover theft, but the bank's fraud liability does.

Why do banks charge overdraft fees?

An overdraft occurs when you spend more than your account balance. The bank covers the difference (a short-term loan) and charges a fee—typically $25 to $35 per transaction. Banks argue this prevents checks from bouncing and merchants from losing money. Critics argue overdraft fees disproportionately harm low-income customers. Many banks now offer overdraft protection (linking to a savings account) or allow you to opt out of overdraft coverage entirely.

Is my money safer at a big bank or a small bank?

Safety depends on FDIC insurance, not bank size. Both large and small banks are FDIC members (with rare exceptions). A small bank and a large bank offer the same $250,000 deposit protection. Large banks may have more sophisticated fraud detection systems, but small banks often have lower fees and more personalized service. The choice is about convenience and cost, not safety.