A double accounting system consists of the two major accounts that are usually invovled in all accounting processes - debit and credit. These two accounts are used in the generall journal to identify the decreasing or increasing in certains accounts (for example, if you were to buy a car with your own money, your bank would be credited, as you are taking money out of bank account - to understand this you would need to know the nature of each of the main accounts; assets, liabilities, revenues, expenses and owners equity).
The debits and credits are also found in the ledger where the information from the journal is usally posted too -
The MAIN basic concept of this is that within the ledger, the debit side and credit side would need to equal each other - this means that the number of debits must equal the number of credits, and if they are not, you will need to use you balance brought down and balance carried down.
A double accounting system is a set of rules for entering finacial information in an accounting system in which each event must be recorded in two different ledger accounts.
In deciding which account has to be debited and which account has to be credited, the golden rules of accounting are used. If at any point the sum of debits for all accounts does not equal the corresponding sum of credits for all accounts, an error has occurred. The sum of debits and the sum of the credits must be equal in value.