In finance, there are four key types of operations that are essential to understand: deposits, withdrawals, repayments, and extensions of credit. Deposits refer to the act of adding funds to an account, while withdrawals involve the removal of funds. Repayments are when a borrower returns money borrowed, and extensions of credit are when a lender grants additional time for repayment. These operations are vital in the world of finance and play a significant role in managing and analyzing financial transactions.