Banks move money, hold it, and lend it out—that is the core of what they do

A bank takes deposits from you, holds them in an account, and uses that money to make loans to other customers. The bank pays you a small amount of interest on what you deposit, charges borrowers a larger amount of interest on what they borrow, and keeps the difference. Beyond that basic exchange, banks offer a range of services tied to moving money in and out, protecting it, and helping you borrow when you need to.

The services you use most often—checking, savings, transfers—are the visible part. Behind them sit less obvious services: fraud protection, payment processing, currency exchange, and connections to other financial systems. Understanding what your bank actually does helps you know which service to use for which situation, and what you are paying for when you pay a fee.

Key Takeaways

  • Banks hold your deposits in checking and savings accounts, pay you interest on savings, and charge you fees if your balance drops below a minimum or you overdraw.
  • Banks process payments you send out—checks, wire transfers, ACH transfers, debit card transactions—and each method takes a different amount of time and costs the bank different amounts to run.
  • Banks lend money in the form of personal loans, mortgages, auto loans, and credit cards, and they make their profit from the interest you pay on borrowed money.
  • Banks protect your deposits up to $250,000 per account type through FDIC insurance, and they monitor accounts for fraud and unauthorized transactions.
  • Banks charge fees for overdrafts, minimum balance violations, wire transfers, and other services, and these fees vary widely between institutions.

Deposit accounts: where your money sits and earns interest

A checking account is designed for frequent deposits and withdrawals. You can write checks, use a debit card, set up automatic bill payments, and transfer money out without limit. Banks typically pay little or no interest on checking balances because the money moves in and out constantly. Some checking accounts charge a monthly fee if you do not maintain a minimum balance—often $500 to $2,500 depending on the bank—or if you fall below it for part of the month.

A savings account is designed to hold money longer. Banks pay interest on savings balances, though the rate varies with the overall interest rate environment and the bank's own policies. The tradeoff is that you can only withdraw money a limited number of times per month—federal rules once capped this at six, though that rule has loosened. Savings accounts also charge monthly fees if your balance drops below a minimum, which ranges from $25 to $500 depending on the bank.

A money market account sits between the two: it pays interest closer to savings rates but allows more frequent withdrawals and often comes with a debit card or checkbook. The minimum balance requirement is usually higher than savings—often $2,500 or more.

Payment processing: how money leaves your account

When you send money out, the bank chooses a method based on how fast you need it to go and how much it costs to process. A debit card transaction clears in one to three business days and costs the bank almost nothing to process, so there is usually no fee to you. A check takes three to five business days to clear because it has to move through the Federal Reserve's check processing system. An ACH transfer (Automated Clearing House) takes one to three business days and is free or costs $1 to $3 because it moves through a batch system that processes thousands of transfers at once.

A wire transfer is the fastest method—money can arrive the same day or next business day—but it costs $15 to $50 because the bank has to process it individually and immediately. Wire transfers are also harder to reverse if you send money to the wrong account. A bill pay service through your bank's website or app typically sends an ACH transfer or check on your behalf, usually free, and takes three to five business days.

Banks also process automatic recurring payments—subscriptions, insurance premiums, loan payments—that you set up once and the bank pulls from your account on a schedule you choose. These are usually ACH transfers and cost nothing.

Lending: how banks make money from borrowed funds

Banks lend money in several forms. A personal loan is a fixed amount you borrow and repay over a set period—usually two to seven years—at a fixed or variable interest rate. You receive the money in one lump sum and make monthly payments. Banks charge interest rates based on your credit score and income; rates typically range from 6% to 36% depending on your creditworthiness and the lender.

A mortgage is a long-term loan secured by the house itself. If you stop paying, the bank can take the house. Mortgages run 15 to 30 years and interest rates are lower than personal loans because the bank has collateral. A home equity line of credit (HELOC) lets you borrow against the equity you have built in your house, draw money as needed, and pay interest only on what you use.

An auto loan works like a mortgage but for a car: the bank lends you money, you repay over three to seven years, and the bank holds the title until you pay off the loan. A credit card is a revolving line of credit—you can borrow up to a limit, pay it back, and borrow again. Interest rates on credit cards are much higher than other loans, typically 15% to 25%, because the bank has no collateral and the debt is unsecured.

Fraud protection and account monitoring

Banks monitor accounts for suspicious activity and will contact you if they see a transaction that does not match your normal pattern—a large purchase in a foreign country, a series of small withdrawals, or a wire transfer to an account you have never used before. This monitoring is not perfect and varies by bank, but it is one layer of protection.

If someone uses your debit card or account number without permission, federal law (Regulation E) limits your liability to $50 if you report it within two business days, and to $500 if you report it within 60 days. After 60 days, you may lose all the money. If someone opens a credit card in your name, that is identity theft and is handled differently—you report it to the credit card company and the Federal Trade Commission, not your bank.

Banks also use encryption to protect your login information and require two-factor authentication (a code sent to your phone or email) on many transactions. This protects against someone logging into your account remotely, though it does not protect against you being tricked into sending money to a scammer.

FDIC insurance: what happens if the bank fails

The Federal Deposit Insurance Corporation (FDIC) insures deposits at member banks up to $250,000 per depositor, per bank, per account type. This means if your bank fails, the FDIC will reimburse you for up to $250,000 in your checking account, up to $250,000 in your savings account, and up to $250,000 in your money market account—three separate limits. If you have more than $250,000 in one account type at one bank, the amount over $250,000 is not protected.

Joint accounts are insured separately: if you and your spouse have a joint checking account with $400,000, each of you is insured for $250,000, so the full amount is covered. Accounts in different names at the same bank are also insured separately—your individual account and your business account each get $250,000 of coverage.

FDIC insurance does not cover investment accounts, brokerage accounts, or money you have loaned to the bank in the form of a certificate of deposit (CD) that has matured and is being held as a non-deposit product. It also does not cover losses from fraud or theft—it only covers the bank failing.

Fees: what banks charge for services

Banks charge fees for several common situations. An overdraft fee (also called an NSF fee, for non-sufficient funds) is charged when you spend more money than you have in your account—typically $25 to $40 per overdraft. Some banks charge multiple overdraft fees in a single day if you make several transactions while overdrawn. A minimum balance fee is charged if your account balance drops below the required minimum, usually $5 to $15 per month.

A wire transfer fee is $15 to $50 depending on whether the wire is domestic or international. An ATM fee is charged if you use an ATM that does not belong to your bank's network—typically $2 to $3 per transaction. A foreign transaction fee is charged when you use your debit card in another country or withdraw cash from a foreign ATM—usually 1% to 3% of the transaction amount.

Some banks charge a monthly maintenance fee just for having the account, though this is often waived if you maintain a minimum balance or set up direct deposit. Banks rarely charge for basic services like transfers between your own accounts, bill pay, or check deposits, but they may charge for services like stopping payment on a check ($25 to $35) or requesting old statements ($5 to $10 per statement).

Frequently Asked Questions

What is the difference between a bank and a credit union?

A bank is a for-profit business owned by shareholders. A credit union is a nonprofit owned by its members. Credit unions often charge lower fees and pay higher interest on savings, but they may have fewer branches and ATMs. Both are insured by the FDIC or NCUA (National Credit Union Administration) up to $250,000.

Can a bank refuse to cash a check?

Yes. A bank can refuse to cash a check if the account it is drawn on does not have enough funds, if the check is stale (more than six months old), or if the bank suspects fraud. If you are the account holder and the check is drawn on your own account, the bank must cash it if you have the funds, though they may charge a fee.

What happens if I do not pay back a loan?

The bank will contact you to collect the debt. If you continue not to pay, the bank may sue you, garnish your wages, or seize collateral (like your car or house). The missed payments will also damage your credit score, making it harder and more expensive to borrow in the future.

Do I need to use my bank for bill payments?

No. You can pay bills directly to the company, through a third-party payment app, or by mailing a check. Using your bank's bill pay service is convenient because it is integrated with your account, but it is not required.

What should I do if I see a transaction I did not make?

Contact your bank immediately by phone—do not wait. Report the unauthorized transaction and ask the bank to freeze your account or issue a new card. The bank will investigate and typically refund the money while they do, though you may be liable for some amount depending on how quickly you reported it.