Balance of payments:

The balance of payments accounts are an integral part of the national income accounts for an open economy. They record (in principle) all  transactions between 'residents' of  the country concerned and those of other countries, where 'residents'  are  broadly interpreted as all individuals, businesses, and governments and their agencies; international organisations are also classified as  'foreign' residents for this purpose.

The balance-of-payments accounts, however, serve  another  purpose.  The balance of a country's foreign transactions, and  the accompanying  issues  of  the exchange rate and reserves  (whether of gold or of foreign currencies) has long been a focus of interest for policy-makers.  

Current account  of  the balance of payments  records transactions  on account of trade in goods and services, unilateral transfers etc. Different financial capital inflows and outflows are recorded in  the capital account. Balance of payments should always balance in the accounting sense, meaning that the sum of all the debit side entries must match with the credit side entries. On account of various reasons some entries do not get properly recorded in the balance of payments. Due to this reason debit and credit side entries often fail to match with each other. Errors and omissions take care of them. Balance of payments in accounting sense must always balance. But that does not  imply that balance of payments will always be  in equilibrium. By equilibrium  in  balance of payments it is meant  that present  liabilities are perfectly matched by the present asset positions of the country with respect to the rest of the world.