An account number is basically a management tool that is used by practically all businesses to keep track of their clients. Various businesses have transactions with countless clients who hold accounts with these businesses. Each account is associated with a certain client, and documentation is kept for each account. The documentation includes various pieces of information, an account number being one of them.
One may think that the name of the account holder should be enough to identify the account. However, in some cases, a single person or entity may have several accounts. Obviously, an account number will be the identifying factor. More so, having a unique number assigned to the account does make it easier to search for the records when the need arises.
The average person has numerous account numbers, depending on the accounts that he holds. For example, one may have several bank accounts - savings, checking, and so on. Each of these accounts will have a unique number assigned. The same thing applies to utilities. Your power provider, telephone provider, water provider, Internet service provider, etc. - all of them have a unique account number assigned to you. Anytime that you need to transact business with them, e.g. pay your bill, your account number will be referenced.
Even small businesses make use of account numbers. For example, a laundry shop that has regular clients can assign account numbers to each client. At the end of the billing period, they can reference the account number to send the invoice.
While the term refers to “number”, an account number may include letters as well.