The trial balance

Requirements for a Trial Balance
Companies initially record their business transactions in bookkeeping accounts within the general ledger. Depending on the kinds of business transactions that have occurred, accounts in the ledgers could have been debited or credited during a given accounting period before they are used in a trial balance worksheet. Furthermore, some accounts may have been used to record multiple business transactions. As a result, the ending balance of each ledger account as shown in the trial balance worksheet is the sum of all debits and credits that have been entered to that account based on all related business transactions.
A company’s transactions are recorded in a general ledger and later summed to be included in a trial balance. 
At the end of an accounting period, the accounts of asset, expense, or loss should each have a debit balance, and the accounts of liability, equity, revenue, or gain should each have a credit balance. However, certain accounts of the former type also may have been credited and certain accounts of the latter type also may have been debited during the accounting period when related business transactions reduce their respective accounts’ debit and credit balances, an opposite effect on those accounts’ ending debit or credit balances. On a trial balance worksheet, all of the debit balances form the left column, and all of the credit balances form the right column, with the account titles placed to the far left of the two columns.
Types of Trial Balance
There are three main types of trial balance:

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  The unadjusted trial balance
  
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  The adjusted trial balance
  
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  The post-closing trial balance
  

All three of these types have exactly the same format but slightly different uses. The unadjusted trial balance is prepared on the fly, before adjusting journal entries are completed. It is a record of day-to-day transactions and can be used to balance a ledger by adjusting entries.
Once a book is balanced, an adjusted trial balance can be completed. This trial balance has the final balances in all the accounts, and it is used to prepare the financial statements. The post-closing trial balance shows the balances after the closing entries have been completed. This is your starting trial balance for the next year.