A check is an antiquated form of money in which a person writes an amount of money on a piece of paper, gives it to another person, and that person gets the money from a bank where the check writer deposited money into a checking account earlier.
Checks are still seen in U.S. society today, although their use is dying out in favor of more convenient forms of payment such as online bill payment, credit cards, and debit cards. Checks are not as favored in countries where the mail service is not as secure as in the U.S.; checks are commonly mailed, therefore they depend on a cheap, secure, predictable, and fast mail system.
Checks have numbers on the bottom called MICR numbers, which contain a routing number which describes the bank and your account number. These numbers are commonly required to set up such features as direct deposit of your paycheck or social security distribution.
And interesting feature of checks is that any piece of paper can be a check. The writer of the check merely has to provide the appropriate information to enable the bank to guarantee that the funds are coming out of the correct account, and to provide their signature authorization. However, retailers and providers of services are not legally required to accept checks as they are U.S. currency, and can and often do require a more secure bank-authorized check with security features and preprinted name and address information of the check writer.