Perhaps the most common function of the modern ATM, withdrawals are usually allowed from a user's savings or checking account.
Similarly, most (but not all) ATMs allow deposits to be made to both checking and savings accounts. These deposit functions sometimes require cash or checks in envelopes, although many ATMs allow you to deposit without the use of envelopes.
Another common function of the ATM is the ability to check account balance, for savings or checking, and to print out that balance for future reference.
Account transfer is a popular function for those who carefully manage the funds in more than one account, and can be used to move funds from one account (for example, a checking account) to another (like a savings account).
An increasingly popular function of modern ATMs is the ability to buy stamps. Although this functionality is not available at all ATMs, its popularity has been sufficient for its availability to expand.