Debit and credit are opposing sides of accounting transactions. Debit represents an increase in assets or expenses, while credit represents a decrease in assets or an increase in income. Transactions are recorded using a double-entry bookkeeping system, where every transaction has an equal debit and credit amount to maintain the accounting equation of assets = liabilities + equity. The key accounting rules are real accounts, which determine whether to debit or credit assets; nominal accounts, which determine whether to debit expenses/losses or credit incomes/gains; and personal accounts, which determine whether to debit the receiver or credit the giver. Maintaining debits and credits according to these rules ensures the accuracy of financial records.