All businesses have transactions and all transactions need to be recorded. For one thing you would have difficulty gauging how well your business was doing without being able to review the various transactions in recorded form. You could look at the bank account for the business on a regular basis to see how much money had been deposited, how much was paid out, or withdrawn in cash, and what the balance was.
But this would only give you a snapshot in time which usually only reveals an incomplete position of the business as a whole. Some of the bills may not actually have been paid out at that time or bills your business has sent out may still be outstanding for payment by customers. If such items are significantly large then the bank balance could well be quite misleading.
Secondly, you need to comply with Government legislation and Tax regulations which require that you maintain records and keep back-up documentation (such as receipts, invoices, bank statements etc) for a specific number of years. In the UK this is 7 years.
And, last, but not least, keeping proper records enable you to analyse data that may indicate trends, or indicate areas of particular profit or loss, such that you could manage your business more effectively.
