Ratio analysis is a valuable analytical technique that allows businesses to study end-of-period financial reports to inform future decisions. Ratios can be presented as percentages or ratios and are used to assess profitability, stability, and effectiveness. Key profitability ratios include gross profit ratio, net profit ratio, and expense-to-sales ratio. These ratios indicate ability to earn income, generate gross/net profit from sales, and control expenses. Higher ratios may suggest good performance while lower ratios could mean inability to cover costs or earn satisfactory profits. Recommendations include improving sales, minimizing costs of goods sold, and setting expense budgets.