A check is a payment agreement between two people or organizations. When you write a check, you are agreeing to pay another person or organization the money you owe them and you are asking your bank to make that payment.
A cashier's check is different from a personal check because the money is drawn from the bank's account. With a personal check, the money is drawn from your account. Certified checks and cashier's checks may be considered "official checks". Both are used in place of cash, credit, or personal checks. They are used to secure payment. It is difficult to replace these types of checks. For a lost cashier's check, you will need to obtain an indemnity guarantee, which you can obtain through an insurance company, but this is often difficult. Your bank may require you to wait up to 90 days for a replacement check.