Business is a collection of transactions. Every transaction includes two aspects one is receiving aspect and the other is giving aspect. to record the business transactions we have two methods one is single entry system and the other is double entry system. Double entry system is a system which records both aspects of the transation i.e. recording giving aspect and receiving aspect. receiving aspect is known as debit aspect whereas giving aspect is konwn as credit aspect.
Book keeping is the recording of transactions relating to money and Double entry book keeping means recording the transaction in two aspects i.e., Debit and Credit. For every debit entry there should be a correspondence credit entry is the principle of Double Entry Booking Keeping.
Double entry system is the system of book keeping which emerged as a better substitute for single entry system..well there is no any method known as single entry system as per accounting standards...thus not to maintain or improper maintenance of books of accounts is single entry system. double entry system of bookkeeping is dat system in which the effects of each transaction is posted twice...i.e. in the ledgers of both the effected accounts.. say if Lokesh has given cash to pankaj..it has two effects...lokesh is giving cash and pankaj is receiving cash... thus entry passed in lokesh's books of accounts will be pankaj a/c.....dr To cash a/c  here the transaction is affecting two sides i.e pankaj a/c and cash a/c..
thus pankaj's a/c will be debited with cash (amount what lokesh has given) and cash a/c will be credited with pankaj a/c with the same amount... this is how double entry system works...
As per accounting standards...double entry system works on the principle of Dual Effect
Simple, double entry book keeping , actually we know that every thing have two aspect , in accounting systems each and every transaction treats as two aspects reciever/giver, what comes/ what goes out from business & all expenses and losses, here every transaction have two aspects mentioned above written in accounting term debit / cretid.So each one treated either debit/ credit as per golden rule of accounting
Double entry book keeping system was first mentioned by "Luca De Bargo Pacioli" in his book Summa de arithmetica in 1494.He was a classmate of Leonardo Da Vinci. The book Summa De Arithmetica was basically about maths and arithmatics. But double entry book keeping system is only mentioned in that book as a chapter.
The basic principle of double entry book keeping system is that each and every transaction has two effects which are opposite to each other. Say when you buy something for cash then that thing "comes in" and cash "goes out". So the transaction must be recorded in 2 places or in 2 accounts.
This system bifurcates the accounts into 2 personal and non-personal. The non-personal accounts are further bifurcated into real and nominal. So in a nutshell the accounts are
a) personal,
b) real and
c) nominal accounts.
The system also states which books need to be maintained.They are:
