It used to be simple: You buy something by paying cash. Now there are lots of choices: checks; credit and debit cards; online transfers; wire transfers; and now Apple Pay.
Your checking account is the account where the day-to-day management of your money takes place. It is the account where you deposit money that you receive either from your paycheck or someplace else, and it is the account from which you pay your bills.
Bills are frequently paid by writing a check to whoever has to be paid each month: Florida Power and Light for the electric bill; Miami-Dade Water and Sewer for the water bill; the lawn mower guy; the propane company for the propane you use for the stove and hot water tanks; the insurance company for your insurance policies; the air-conditioning repair company; the Visa and American Express bills; and so on.
Writing checks takes some time, but it is a good way to keep track of what you are spending. After a check is written, you make an entry in your checkbook register, which is a permanent record of whom you paid, the check number, the date you made the payment, and the amount of the payment.
Checkbook registers record payments made and deposits received: money in; money out. By carefully recording what you deposit and what you spend, you will know exactly how much money you have available to spend.
The following is a copy of a checkbook register:
The money you have in your checking account ...