What do the three numbers at the bottom of the check stand for?

Routing number, account number and check number

Explanation:

There are three numbers present at the bottom of the check. On the left side or the first number is a nine digit number that is also called RTN, is routing number. This represents the code of the bank where the account was opened.

Second number in the middle is the account number which is a unique number. All transactions are carried out using this number.

The last number on the right side is the check number. It just represents the check number that one is writing to maintain records.

Routing number, account number and check number