A trial balance (OR a list of account balances) is a list of all ledger balances (which form part of the double entry system only) shown in debit and credit columns. The totals of each columns should be the same if all debits and credits are entered systematically.
The trial balance is not a financial document officially, but it is just a method used to test the accuracy of the double entry bookkeeping methods. Because of this, the exact format may vary but in practice many trial balance reports appear very similar. A common format is to list the balance sheet accounts first, followed by the income statement accounts.