A bank is a business that holds your money, lends it out, and makes profit on the difference between what it pays you and what it charges borrowers

When you put money into a checking or savings account, the bank doesn't lock it in a vault with your name on it. Instead, the bank uses your deposit as part of a pool of funds it lends to other customers — for mortgages, car loans, credit cards, business lines of credit. You earn interest (usually very small) on what you keep there. The bank charges borrowers much higher interest. That gap is how banks make money.

The bank is legally required to give your money back when you ask for it. That promise is what makes the system work. You trust the bank will have your funds available, and the bank trusts it can lend out most of what customers deposit because not everyone withdraws at the same time. If a bank runs out of money and can't pay depositors, the Federal Deposit Insurance Corporation (FDIC) — a government agency — covers up to $250,000 per person per bank account type.

Banks are regulated by multiple government bodies. The Office of the Comptroller of the Currency (OCC) oversees national banks. State banking regulators oversee state-chartered banks. The Federal Reserve sets interest rates and reserve requirements that affect how much banks can lend. This regulation exists because a bank failure can harm thousands of people at once.

Key Takeaways

  • Banks profit by paying you low interest on deposits and charging borrowers higher interest on loans.
  • Your deposits are insured up to $250,000 per account type by the FDIC if the bank fails.
  • Banks are required to keep a portion of deposits on hand and cannot lend out every dollar customers deposit.
  • Multiple government agencies regulate banks to prevent failures and protect depositors.
  • The money you deposit is not sitting in a separate account — it enters a shared pool the bank uses for lending.

How banks make money from your account

A bank's revenue comes almost entirely from the interest spread. If you have $10,000 in a savings account earning 0.01% annually, you earn $1 per year. The bank takes that same $10,000 and lends it to a mortgage borrower at 6.5% interest. The borrower pays $650 per year on that portion of the loan. The bank keeps the difference: $649.

Banks also charge fees — overdraft fees when you spend more than you have, monthly maintenance fees on certain accounts, ATM fees if you use another bank's machine, wire transfer fees. These fees are separate from the interest spread and represent a growing share of bank revenue, especially for large banks. Some banks waive fees if you maintain a minimum balance or set up direct deposit.

A small portion of bank revenue comes from services: they charge businesses for payroll processing, charge investors for managing portfolios, charge merchants a percentage of each credit card transaction. But for a person with a checking account, the bank's main profit source is lending out your deposits at a higher rate than it pays you.

Why banks need to keep some money on hand

Banks cannot lend out every dollar deposited. Federal Reserve rules require banks to hold a minimum percentage of customer deposits as reserves — money that must stay in the bank and cannot be loaned out. The reserve requirement varies by the size and type of bank, but it typically ranges from 0% to 10% depending on the account type and current Fed policy.

Reserves exist for two reasons. First, they may support a bank can pay customers who want to withdraw money. If everyone with a bank account tried to withdraw on the same day, the bank would fail — this is called a bank run. Reserves make a run less likely because the bank can actually pay out cash. Second, reserves give regulators a tool to control how much money is circulating in the economy. When the Fed raises the reserve requirement, banks have less to lend, which slows borrowing and spending.

During the 2008 financial crisis, the Federal Reserve temporarily lowered reserve requirements to nearly zero to encourage banks to lend more and prevent a collapse. This shows how reserve rules are a policy tool, not just a safety measure.

The difference between banks and other financial institutions

Not every place that holds money is a bank. Credit unions are member-owned cooperatives that work similarly to banks but return profits to members rather than shareholders. Savings and loan associations historically focused on mortgages but now operate much like banks. Money market funds invest your deposits in short-term loans and securities rather than making traditional bank loans. Brokerage firms hold money but primarily for investing in stocks and bonds, not for lending.

The key difference is what they do with your money and what regulation they fall under. A bank takes deposits and makes loans. A brokerage takes deposits and buys securities. A credit union takes deposits and makes loans but is owned by members. A money market fund takes deposits and buys short-term debt instruments. Each has different rules about what they can do with your money and different insurance protections.

For everyday checking and savings, the distinction matters less than you might think. A credit union checking account works almost identically to a bank checking account. The main practical difference is that credit unions are often smaller and may have fewer ATMs, while banks have more branches and ATMs but may charge more fees.

What happens to your money after you deposit it

When you deposit a check or transfer money into your bank account, the bank credits your account when ready — you see the balance right away. But the money doesn't physically move to your account. Instead, the bank records that it owes you that amount. The actual check or transfer clears through a separate system over the next one to three business days.

During that clearing period, the bank has temporary use of the funds. If you deposit a check on Friday, the bank may not receive the actual money from the check writer's bank until Monday. But your account shows the deposit on Friday. This is why banks can place a hold on deposits — they're protecting themselves in case the check bounces or the transfer fails.

Once the money clears, it enters the bank's general pool of deposits. The bank then lends portions of that pool to other customers. Your specific dollars don't stay in a separate vault. The bank tracks how much it owes you (your balance) and how much it has lent out, but the actual cash and electronic transfers are mixed together in the bank's operations.

How bank failures happen and what protects you

A bank fails when it runs out of money to pay depositors. This usually happens because the bank made too many bad loans — borrowers stopped paying back mortgages, business loans went unpaid, credit card borrowers defaulted. The bank's losses exceed its capital, and it cannot cover the gap.

When a bank fails, the FDIC takes over. It pays depositors up to $250,000 per person per account type. If you have $300,000 in a savings account at a failed bank, the FDIC pays you $250,000 and you lose $50,000. If you have $200,000 in a savings account and $100,000 in a checking account at the same bank, both are fully covered because they are different account types.

The FDIC insurance fund is built from fees banks pay — not from tax dollars. When a bank fails, the FDIC sells the bank's assets (the loans it made, the building, the equipment) to recover money. Most depositors are paid within days. Bank failures are rare in the modern era because regulation is strict and the FDIC's existence makes people less likely to panic and withdraw all at once.

Why interest rates on savings are so low

Banks pay very low interest on savings accounts — often 0.01% to 0.5% annually — because they don't need to pay more. Deposits are stable and reliable. People keep money in savings accounts for safety, not to maximize returns. Banks know this, so they offer minimal interest.

When the Federal Reserve raises its benchmark interest rate, banks eventually raise the rates they pay on savings accounts, but the increase lags by weeks or months. When the Fed lowers rates, banks drop savings rates almost when ready. This asymmetry is another way banks protect their profit margin.

High-yield savings accounts, offered by online banks and some traditional banks, pay 4% to 5% annually in the current environment. These banks can afford higher rates because they have lower overhead — no physical branches, fewer employees. They pass some of that savings to customers in the form of higher interest. But even high-yield rates are lower than what banks charge borrowers, so the profit margin still exists.

Frequently Asked Questions

What happens if I keep more than $250,000 in one bank?

Only $250,000 per account type is insured by the FDIC. If you have $500,000 in a savings account, $250,000 is covered and $250,000 is not. You can increase coverage by opening accounts in different names (a joint account with your spouse counts as a separate $250,000 limit) or by using different account types at the same bank (savings, checking, and money market are separate limits).

Can a bank use my money without my permission?

A bank uses your deposits to make loans as part of normal operations — that's how it makes profit. You give permission by opening an account. However, a bank cannot take your money to cover its own losses or debts. If a bank fails, the FDIC protects your deposits up to $250,000. A bank also cannot freeze your account without legal reason, such as a court order or suspected fraud.

Why do banks charge overdraft fees if they're already making money from lending?

Overdraft fees are additional revenue. When you overdraw, the bank is technically making a short-term loan to cover the negative balance, so the fee is partly a loan fee. But banks also charge overdraft fees because they can — customers often don't notice or don't have alternatives. Some banks now offer overdraft protection that links to a savings account or credit line instead of charging a fee.

Is my money safer in a bank or a credit union?

Both are equally safe up to $250,000. Banks are insured by the FDIC. Credit unions are insured by the National Credit Union Administration (NCUA), which operates the same way. Both agencies may provide deposits if the institution fails. The choice between a bank and credit union should be based on fees, interest rates, and convenience, not safety.

What's the difference between a bank and a digital bank?

A digital bank (or online bank) operates the same way as a traditional bank — it takes deposits, makes loans, and is regulated and insured the same way. The difference is operational: digital banks have no physical branches. You manage your account through an app or website. Digital banks typically charge fewer fees and pay higher interest on savings because they have lower overhead costs.