Ratios are used to analyze various aspects of a business's performance including liquidity, shareholders returns, efficiency, and profitability. Key ratios discussed include the current ratio and acid test ratio for liquidity, dividends per share and dividend yield for shareholders, gearing and asset turnover for efficiency, and gross profit margin, net profit margin, and return on capital employed for profitability. Limitations of ratio analysis include the need to compare ratios over time, between companies, and across industries to fully understand a business's performance.