Answer
Double-entry bookkeeping records every transaction with equal debits and credits in at least two accounts, reflecting that every transaction has two effects. It keeps the accounting equation (Assets = Liabilities + Capital) in balance and underpins the trial balance and financial statements.
Buy stock for cash 500: Dr Purchases 500; Cr Cash 500.Real-world example Paying rent both decreases cash and increases an expense, captured by equal debit and credit entries.