One of important system of bookkeeping is double entry system. This system was developed by a Francis Lucas pacioli. As per double entry system of bookkeeping, we record every transaction in two side. One side will be debit side and other side will be credit side. We never record one side in this system.
You know, when any business transaction happens, there will be two result will come from us. For example, we sell the goods of Rs. 2000. It means on side, we have sold but its other result is that other party has bout the goods. So, with this transaction, one party is the receiver and other party is the giver. Like this, double entry system classify each transactions into two parts. Every transaction is recorded in the party who has gotten the benefit and who has given the benefit. Every debit side amount will be equal to the credit side amount.
This system is the improvement of single entry system and it is very scientific system for recording the transaction.