Cashier's check
In one sentenceA check the bank issues on its own account after deducting its value from the customer's account, so payment is guaranteed and it cannot be returned for insufficient funds.
Simply put
When the seller wants assurance that the money really exists, a cashier's check is used: the bank deducts the amount from your account immediately and issues the check in the beneficiary's name.
In the books the deduction from the bank is recorded on the issue date, because the money left your account before the beneficiary cashed it.
Example
A business buying used equipment from a seller who does not accept an ordinary check asks its bank for a cashier's check for the amount, and it is deducted from its account the same day.
Don't confuse it with
Returned checkAn ordinary check may be returned, while a cashier's check is guaranteed by the bank.